Member States Etats membres

Austria AllemagneBelgium AutricheDenmark BelgiqueFinland DanemarkFrance EspagneGermany FinlandeGreece FranceIreland GrèceItaly IrlandeLuxembourg ItalieNetherlands LuxembourgNorway NorvègePortugal Pays-BasSpain PortugalSweden Royaumi-UniSwitzerland SuèdeUnited Kingdom Suisse

ESA CommunicationsESTEC, PO Box 299, 2200 AG Noordwijk, The NetherlandsTel: +31 71 565-3400 Fax: +31 71 565-5433Visit Publications at http://www.esa.int

ESA bulletin 131 - august 2007

SPACE FOR EUROPE

number 131 - august 2007

ww

w.esa.int

B131 8/1/07 4:08 PM Page 1

european space agency

The European Space Agency was formed out of, and took over the rights and obligations of, the two earlier European space organisations – theEuropean Space Research Organisation (ESRO) and the European Organisation for the Development and Construction of Space Vehicle Launchers(ELDO). The Member States are Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Norway,Portugal, Spain, Sweden, Switzerland and the United Kingdom. Canada is a Cooperating State.

In the words of its Convention: the purpose of the Agency shall be to provide for and to promote for exclusively peaceful purposes, cooperation amongEuropean States in space research and technology and their space applications, with a view to their being used for scientific purposes and for operationalspace applications systems:

(a) by elaborating and implementing a long-term European space policy, by recommending space objectives to the Member States, and by concertingthe policies of the Member States with respect to other national and international organisations and institutions;

(b) by elaborating and implementing activities and programmes in the space field;(c) by coordinating the European space programme and national programmes, and by integrating the latter progressively and as completely as

possible into the European space programme, in particular as regards the development of applications satellites;(d) by elaborating and implementing the industrial policy appropriate to its programme and by recommending a coherent industrial policy to the

Member States.

The Agency is directed by a Council composed of representatives of the Member States. The Director General is the chief executive of the Agency andits legal representative.

The ESA HEADQUARTERS are in Paris.

The major establishments of ESA are:

THE EUROPEAN SPACE RESEARCH AND TECHNOLOGY CENTRE (ESTEC), Noordwijk, Netherlands.

THE EUROPEAN SPACE OPERATIONS CENTRE (ESOC), Darmstadt, Germany.

ESRIN, Frascati, Italy.

Chairman of the Council: S. Wittig

Director General: J.-J. Dordain

agence spatiale européenne

L’Agence Spatiale Européenne est issue des deux Organisations spatiales européennes qui l’ont précédée – l’Organisation européenne de recherchesspatiales (CERS) et l’Organisation européenne pour la mise au point et la construction de lanceurs d’engins spatiaux (CECLES) – dont elle a repris lesdroits et obligations. Les Etats membres en sont: l’Allemagne, l’Autriche, la Belgique, le Danemark, l’Espagne, la Finlande, la France, la Grèce,l’Irlande, l’Italie, le Luxembourg, la Norvège, les Pays-Bas, le Portugal, le Royaumi-Uni, la Suède et la Suisse. Le Canada bénéficie d’un statut d’Etatcoopérant.

Selon les termes de la Convention: l’Agence a pour mission d’assurer et de développer, à des fins exclusivement pacifiques, la coopération entre Etatseuropéens dans les domaines de la recherche et de la technologie spatiales et de leurs applications spatiales, en vue de leur utilisation à des finsscientifiques et pour des systèmes spatiaux opérationnels d’applications:

(a) en élaborant et en mettant en oeuvre une politique spatiale européenne à long terme, en recommandant aux Etats membres des objectifs enmatière spatiale et en concertant les politiques des Etats membres à l’égard d’autres organisations et institutions nationales et internationales;

(b) en élaborant et en mettant en oeuvre des activités et des programmes dans le domaine spatial;(c) en coordonnant le programme spatial européen et les programmes nationaux, et en intégrant ces derniers progressivement et aussi

complètement que possible dans le programme spatial européen, notamment en ce qui concerne le développement de satellites d’applications;(d) en élaborant et en mettant en oeuvre la politique industrielle appropriée à son programme et en recommandant aux Etats membres une politique

industrielle cohérente.

L’Agence est dirigée par un Conseil, composé de représentants des Etats membres. Le Directeur général est le fonctionnaire exécutif supérieur del’Agence et la représente dans tous ses actes.

Le SIEGE de l’Agence est à Paris.

Les principaux Etablissements de l’Agence sont:

LE CENTRE EUROPEEN DE RECHERCHE ET DE TECHNOLOGIE SPATIALES (ESTEC), Noordwijk, Pays-Bas.

LE CENTRE EUROPEEN D’OPERATIONS SPATIALES (ESOC), Darmstadt, Allemagne.

ESRIN, Frascati, Italy.

Président du Conseil: S. Wittig

Directeur général: J.-J. Dordain

Editorial/Circulation OfficeESA CommunicationsESTEC, PO Box 299, 2200 AG NoordwijkThe NetherlandsTel: +31 71 565-3400

EditorsAndrew WilsonCarl Walker

Design & LayoutIsabel Kenny

AdvertisingLorraine Conroy

The ESA Bulletin is published by the European SpaceAgency. Individual articles may be reprinted providedthe credit line reads ‘Reprinted from ESA Bulletin’, plusdate of issue. Signed articles reprinted must bear theauthor’s name. Advertisements are accepted in goodfaith; the Agency accepts no responsibility for theircontent or claims.

Copyright © 2007 European Space Agency

Printed in the Netherlands ISSN 0376-4265

www.esa.int

This Envisat image features the ice-connectedQueen Elizabeth Islands, Baffin Island and thenorthwestern tip of Greenland – the world’slargest island. The scene was captured byEnvisat’s Medium Resolution ImagingSpectrometer (MERIS) on 2 July 2007 at aresolution of 300 m. (ESA)

IFCb131 8/1/07 4:30 PM Page 2

Sentinel-1Radar Imaging for GMES Land and Sea

Services

Sentinel-2High-Resolution Imaging for GMES

Operational Services

A New Earth ExplorerThe Third Cycle of Core Earth Explorers

Sentinel-1 10

The Radar Mission for

GMES Land and Sea Services

Evert Attema et al.

Sentinel-2 18

The Optical High-Resolution Mission for

GMES Operational Services

Philippe Martimort et al.

Sentinel-3 24

The Ocean and Medium-Resolution Mission for

GMES Operational Services

Miguel Aguirre et al.

A New Earth Explorer 30

The Third Cycle of Core Earth Explorers

Paolo Bensi et al.

www.esa.int esa bulletin 131 - august 2007 1

SMART-1 Impact on the Moon 38

Moon Science, Orbit Reboosts and Impact Observations

Octavio Camino et al.

Powering the Future 46

A New Generation of High-Power Solar Arrays

Freddy Geyer, Doug Caswell & Carla Signorini

Programmes in Progress 50

News – In Brief 64

Publications 72

bulletin 131 - august 2007 Contents

18

Sentinel-3Ocean and Medium-Resolution Imaging

for GMES Operational Services

24

30

Powering the FutureA New Generation of High-Power Solar

Arrays

46SMART-1 Impacts the MoonMoon Science, Orbit Reboosts and

Impact Observations

38

10

ContentsB131 8/1/07 4:33 PM Page 3

Sentinel-1

The ESA Sentinels will be the first series of

loperational satellites to meet the Earthobservation needs of the European Union-

ESA Global Monitoring for Environment andSecurity (GMES) programme. Existing andplanned space assets will be complemented bynew developments from ESA. The first isSentinel-1, a pair of synthetic aperture radar(SAR) imaging satellites.

IntroductionESA is developing the Sentinel-1 Euro-pean Radar Observatory, a polar-orbiting satellite for operational SARapplications. The constellation of twoC-band radar satellites will providecontinuous all-weather day/night imageryfor user services, especially thoseidentified in ESA’s GMES serviceelements programme and on projectsfunded by the European Union (EU)Framework Programmes. Three priori-ties (‘fast-track services’) have beenidentified by EU user working groups:marine core services; land monitoring;and emergency services. These include:

– monitoring sea-ice zones and theArctic;

Evert Attema, Piere Bargellini, Peter Edwards,Guido Levrini, Svein Lokas, Ludwig Moeller,Betlem Rosich-Tell, Patrizia Secchi, RamonTorres, Malcolm Davidson & Paul SnoeijDirectorate of Earth Observation Programmes,ESTEC, Noordwijk, The Netherlands

esa bulletin 131 - august 2007 11

Sentinel-1

The Radar Mission for GMES

Operational Land and Sea Services Envisat radar image of the Solent between the Isle ofWight and Portsmouth, UK. Resolution is 30 m. At thetime, in June 2005, Britain’s navy was gathering for afleet review

Attema 8/1/07 4:51 PM Page 10

Sentinel-1

The ESA Sentinels will be the first series of

loperational satellites to meet the Earthobservation needs of the European Union-

ESA Global Monitoring for Environment andSecurity (GMES) programme. Existing andplanned space assets will be complemented bynew developments from ESA. The first isSentinel-1, a pair of synthetic aperture radar(SAR) imaging satellites.

IntroductionESA is developing the Sentinel-1 Euro-pean Radar Observatory, a polar-orbiting satellite for operational SARapplications. The constellation of twoC-band radar satellites will providecontinuous all-weather day/night imageryfor user services, especially thoseidentified in ESA’s GMES serviceelements programme and on projectsfunded by the European Union (EU)Framework Programmes. Three priori-ties (‘fast-track services’) have beenidentified by EU user working groups:marine core services; land monitoring;and emergency services. These include:

– monitoring sea-ice zones and theArctic;

Evert Attema, Piere Bargellini, Peter Edwards,Guido Levrini, Svein Lokas, Ludwig Moeller,Betlem Rosich-Tell, Patrizia Secchi, RamonTorres, Malcolm Davidson & Paul SnoeijDirectorate of Earth Observation Programmes,ESTEC, Noordwijk, The Netherlands

esa bulletin 131 - august 2007 11

Sentinel-1

The Radar Mission for GMES

Operational Land and Sea Services Envisat radar image of the Solent between the Isle ofWight and Portsmouth, UK. Resolution is 30 m. At thetime, in June 2005, Britain’s navy was gathering for afleet review

Attema 8/1/07 4:51 PM Page 10

– surveillance of the marine environment;– monitoring land movements; – mapping land surfaces: forest, water

and soil, agriculture;– mapping for humanitarian aid in crisis

situations.

The first satellite is expected to belaunched in 2011 aboard a Soyuz fromKourou.

ESA’s SAR HeritageA first glimpse of the potential ofimaging radar from space was providedby the short-lived but successful USSeasat satellite in 1978. ESA’s ownprogramme to develop advanced micro-wave radar instruments culminated withthe launches of ERS-1 (17 July 1991)and ERS-2 (20 April 1995). Remark-ably, ERS-2 is still operating.

ERS demonstrated for the first timethe feasibility of flying reliable, stableand powerful radar imaging systems inspace. The dependability and all-weather capability of the instrumentsalso provided a foundation for develop-ing and exploiting radar images for awide variety of applications. While theinitial objectives for ERS-1 at launchwere predominantly oceanographic,other applications were consideredduring the project’s preparation. TheESA Remote Sensing Advisory Groupin 1974, for example, emphasisedcommercial applications such asagriculture, land-use mapping, waterresources, overseas aid and mapping ofmineral resources in its advice on ERSobjectives.

The rigorous design of the ERS SARhardware – emphasising instrumentstability in combination with accurateand well-calibrated data products –created new opportunities for scientificdiscovery, revolutionised many Earthscience disciplines and laid thefoundations for commercial applica-tions.

For example, ‘SAR interferometry’,which can track land shifts of only a fewmillimetres, was developed mainly usingERS data and is now commonly used inEarth sciences and commercial applica-

and sea-ice monitoring require dailyrevisits (mostly at northern latitudes)and delivery of data within an hour ofacquisition. In contrast, land servicesinvolving interferometry and coverclassification require global coverageevery 2 weeks at most and consistentdatasets.

tions. The potential of space radarsviewing the same scene only a short timeapart was demonstrated in 1995 and1996 during the ERS ‘tandem mission’,when the orbits of ERS-1 and ERS-2were carefully matched but with a 1-daygap.

An important milestone was thelaunch of the Advanced SAR (ASAR)on Envisat on 28 February 2002. Thisensured the continuation of C-banddata and added enhanced capabilitiessuch as wide swaths and dualpolarisation, features that have sincerapidly been integrated into andexploited by many applications. Thearchive of radar data since 1991 isextremely valuable for science andapplications, providing a consistent setof data spanning 16 years.

Service Reliability: A New ChallengeThe operational requirements present anew challenge for spaceborne radar.Unlike its ERS and Envisat experimen-tal predecessors, which supply data tousers on a best-effort basis, operationalsatellites like Sentinel-1 must satisfy userrequirements and supply information in

a reliable fashion. The data provideraccepts legal responsibility for deliveringthe information. Acquisition failuresowing to conflicting requests from users(such as requesting different instrumentmodes at the same time and place)cannot be tolerated.

Sentinel-1 will work largely in aprogrammed conflict-free mannerimaging all landmasses, coastal zonesand shipping routes globally, andcovering the oceans with imagettes. Thisway, the reliability demanded byoperational services is achieved and aconsistent long-term data archive isbuilt for applications based on longtime-series.

Sentinel-1 revisit frequency and coverageare dramatically improved with respectto ERS and Envisat. The orbits of thetwo-satellite constellation repeat every6 days, and conflict-free operationsallow every single data-take to beexploited. The effective revisit andcoverage performance could be furtherimproved by access to Canada’s plannedSAR constellation.

User needs at both high and medium

What GMES Users WantData products from ESA’s successfulERS-1, ERS-2 and Envisat missionsform the basis for many of the pilotGMES services. Sentinel-1 mustmaintain these quality levels in terms ofspatial resolution, sensitivity, accuracy,polarisation and wavelength. Feedbackfrom users indicate unambiguously thatthe crucial requirements for operationalsustainable services are continuity ofdata, frequent revisits, geographicalcoverage and timeliness.

Compared to the current satellites inorbit, substantial improvements of dataprovision in terms of revisit frequency,coverage, timeliness and reliability ofservice are required. As an example,services encompassing ship and oil-spilldetection, wind speed measurements

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 1312

The flooded Elbe River in Germany, demonstrating the value of ‘dual-polarisation’ radar coverage for land-cover classification. Envisat transmits and detects radar waves polarised in the horizontal andvertical directions, yielding more extensive information than could a single polarisation on the ground surface reflecting them. Sentinel-1 will exploit this feature

An Envisat ASAR image in the Arctic’s Beaufort Sea, demonstrating the ability of SAR to distinguish clearly between the thinner, morenavigable first-year ice and the hazardous, much thicker multi-year ice. (Canadian Ice Service)

Radar Interferometry: How it Works

If light travels paths of different lengths, the

observed brightness is either increased or

reduced depending on the wavelength

(colour) and the path length difference.

This ‘constructive’ and ‘destructive’

interference shows up nicely as beautiful

rainbow-like patterns when sunlight reflects

off a thin film of oil (far right).

Radar waves can be made to behave in the same way when they

are bounced off the Earth. If the satellite comes back another time in

exactly the same orbit and the surface has not moved, adding the

two measurements gives a brighter image because of constructive

interference. However, if parts of the surface have shifted between

observations, the destructive interference could dim areas of the

combined images.

So combining two radar images from before and after an

earthquake, for example, generates rainbow-like patterns from which

surface movement can be determined to within typically 1 mm/year.

Attema 8/1/07 4:51 PM Page 12

– surveillance of the marine environment;– monitoring land movements; – mapping land surfaces: forest, water

and soil, agriculture;– mapping for humanitarian aid in crisis

situations.

The first satellite is expected to belaunched in 2011 aboard a Soyuz fromKourou.

ESA’s SAR HeritageA first glimpse of the potential ofimaging radar from space was providedby the short-lived but successful USSeasat satellite in 1978. ESA’s ownprogramme to develop advanced micro-wave radar instruments culminated withthe launches of ERS-1 (17 July 1991)and ERS-2 (20 April 1995). Remark-ably, ERS-2 is still operating.

ERS demonstrated for the first timethe feasibility of flying reliable, stableand powerful radar imaging systems inspace. The dependability and all-weather capability of the instrumentsalso provided a foundation for develop-ing and exploiting radar images for awide variety of applications. While theinitial objectives for ERS-1 at launchwere predominantly oceanographic,other applications were consideredduring the project’s preparation. TheESA Remote Sensing Advisory Groupin 1974, for example, emphasisedcommercial applications such asagriculture, land-use mapping, waterresources, overseas aid and mapping ofmineral resources in its advice on ERSobjectives.

The rigorous design of the ERS SARhardware – emphasising instrumentstability in combination with accurateand well-calibrated data products –created new opportunities for scientificdiscovery, revolutionised many Earthscience disciplines and laid thefoundations for commercial applica-tions.

For example, ‘SAR interferometry’,which can track land shifts of only a fewmillimetres, was developed mainly usingERS data and is now commonly used inEarth sciences and commercial applica-

and sea-ice monitoring require dailyrevisits (mostly at northern latitudes)and delivery of data within an hour ofacquisition. In contrast, land servicesinvolving interferometry and coverclassification require global coverageevery 2 weeks at most and consistentdatasets.

tions. The potential of space radarsviewing the same scene only a short timeapart was demonstrated in 1995 and1996 during the ERS ‘tandem mission’,when the orbits of ERS-1 and ERS-2were carefully matched but with a 1-daygap.

An important milestone was thelaunch of the Advanced SAR (ASAR)on Envisat on 28 February 2002. Thisensured the continuation of C-banddata and added enhanced capabilitiessuch as wide swaths and dualpolarisation, features that have sincerapidly been integrated into andexploited by many applications. Thearchive of radar data since 1991 isextremely valuable for science andapplications, providing a consistent setof data spanning 16 years.

Service Reliability: A New ChallengeThe operational requirements present anew challenge for spaceborne radar.Unlike its ERS and Envisat experimen-tal predecessors, which supply data tousers on a best-effort basis, operationalsatellites like Sentinel-1 must satisfy userrequirements and supply information in

a reliable fashion. The data provideraccepts legal responsibility for deliveringthe information. Acquisition failuresowing to conflicting requests from users(such as requesting different instrumentmodes at the same time and place)cannot be tolerated.

Sentinel-1 will work largely in aprogrammed conflict-free mannerimaging all landmasses, coastal zonesand shipping routes globally, andcovering the oceans with imagettes. Thisway, the reliability demanded byoperational services is achieved and aconsistent long-term data archive isbuilt for applications based on longtime-series.

Sentinel-1 revisit frequency and coverageare dramatically improved with respectto ERS and Envisat. The orbits of thetwo-satellite constellation repeat every6 days, and conflict-free operationsallow every single data-take to beexploited. The effective revisit andcoverage performance could be furtherimproved by access to Canada’s plannedSAR constellation.

User needs at both high and medium

What GMES Users WantData products from ESA’s successfulERS-1, ERS-2 and Envisat missionsform the basis for many of the pilotGMES services. Sentinel-1 mustmaintain these quality levels in terms ofspatial resolution, sensitivity, accuracy,polarisation and wavelength. Feedbackfrom users indicate unambiguously thatthe crucial requirements for operationalsustainable services are continuity ofdata, frequent revisits, geographicalcoverage and timeliness.

Compared to the current satellites inorbit, substantial improvements of dataprovision in terms of revisit frequency,coverage, timeliness and reliability ofservice are required. As an example,services encompassing ship and oil-spilldetection, wind speed measurements

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 1312

The flooded Elbe River in Germany, demonstrating the value of ‘dual-polarisation’ radar coverage for land-cover classification. Envisat transmits and detects radar waves polarised in the horizontal andvertical directions, yielding more extensive information than could a single polarisation on the ground surface reflecting them. Sentinel-1 will exploit this feature

An Envisat ASAR image in the Arctic’s Beaufort Sea, demonstrating the ability of SAR to distinguish clearly between the thinner, morenavigable first-year ice and the hazardous, much thicker multi-year ice. (Canadian Ice Service)

Radar Interferometry: How it Works

If light travels paths of different lengths, the

observed brightness is either increased or

reduced depending on the wavelength

(colour) and the path length difference.

This ‘constructive’ and ‘destructive’

interference shows up nicely as beautiful

rainbow-like patterns when sunlight reflects

off a thin film of oil (far right).

Radar waves can be made to behave in the same way when they

are bounced off the Earth. If the satellite comes back another time in

exactly the same orbit and the surface has not moved, adding the

two measurements gives a brighter image because of constructive

interference. However, if parts of the surface have shifted between

observations, the destructive interference could dim areas of the

combined images.

So combining two radar images from before and after an

earthquake, for example, generates rainbow-like patterns from which

surface movement can be determined to within typically 1 mm/year.

Attema 8/1/07 4:51 PM Page 12

resolution have meant so far that SARsystems include different operationalmodes that either optimise the spatialresolution (at the expense of the swathwidth, hence the coverage) or the swathwidth (at the expense of the resolution).GMES will provide access to very high-resolution SAR national missions(Germany’s TerraSAR-X and Italy’sCosmo-SkyMed), so Sentinel-1 isdesigned to address medium-resolutionapplications with its main mode: a wideswath (250 km) and medium resolution(5 x 20 m).

Products for Marine Core ServicesSAR is the primary source of data forinformation on the oceans and theArctic environment. The problems ofaccess to the open oceans and the harshArctic often make radar, with its abilityfor observations in all weather and dayor night, the only reliable informationsource. Typical products for the ice andsnow services include monitoringglaciers and snow, icebergs, sea ice (floeedge) and the near-shore ice complex.

For determining the direction, wave-length and (extreme) heights of waveson the open oceans, SAR imagettes arebeing used in near-realtime inconjunction with global ocean wavemodels. The extensive wave modearchive built up by ERS and Envisat is acritical resource for analysing regionalwave climate and extreme wave events.

ERS-1/2 tandem mission.During the ERS tandemphase, data pairs werecollected on successivedays.

Classifying land coveris not the only importantapplication of SAR toland monitoring. Sincei n t e r f e r o m e t r i c radar can detect surfacemovements to within afew millimetres per year,it is now an establishedtechnique to monitor theeffects of landslides,earthquakes and man-made activities such asbuilding construction,tunnelling, water ornatural gas extraction,and mining.

Products for Emergency ServicesIts all-weather day/night capability makesspace-borne radar the ideal workhorsefor providing information before, duringand after emergencies. Sentinel-1’s two-satellite constellation will routinely revisitall sites within 3 days at the equator andimproving with latitude. In addition, anoptional emergency procedure couldaccelerate access.

Agreements with other satelliteoperators will make daily access or evenbetter a realistic assumption. Thisexcellent revisit performance is feasibleeven while maintaining a spatialresolution of 5 x 20 m. In order toobserve finer detail, regional coverage bysatellites with higher spatial resolution(radar and/or optical) will be required.

Sentinel-1 will build a multi-temporalglobal interferometric image archive thatcan be called on in emergency situations.

SAR is also the primary source ofinformation on oil spills, such assurveillance and drift forecasting, and onship detection for fisheries and security.

Products for Land Monitoring ServicesSAR data are not always the primarysource for basic land-cover classification(forest, agricultural crops, urban areas,etc.) if multi-channel optical imagerywith high spatial resolution is available.However, SAR is commonly used as acomplementary or alternative datasource under adverse atmosphericconditions such as cloud cover.

The contribution made by SAR tobasic land-cover classification wasgreatly increased by the ‘dual polarisa-tion’ mode introduced by Envisat’sASAR. Because the reflective propertiesof a surface depend on the polarisationof the incoming signal, the use of morethan one type of polarisation providesvaluable extra information. This hasbecome a favourite for land classifica-tion. For this reason, Sentinel-1 isdesigned to exploit the full capabilitiesofferred by dual polarisation.

A dramatic improvement is expectedfrom the more frequent revisits to thesame area by Sentinel-1. This featureenhances time-series by adding close todaily sampling. Combined with itsinterferometric capability, Sentinel-1will routinely offer products that wereonly available experimentally from the

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 1514

Sentinel-1

Revisiting a scene only a day later allows interferometry todistinguish between water bodies, forest, urban areas andagriculture. In this single ERS-1/ERS-2 image pair overThe Netherlands, colours are assigned so that generally treesappear green, water appears blue and agricultural fields appearorange

Oil from a wrecked tanker had already reached the northwest coast of Spain whenEnvisat acquired this radar image on 17 November 2002

Map of the flooding in the Timis region of Romania in May 2005, based on Envisat ASAR Narrow Swath and SPOT-5 data. (Image processing and map creation by DLR; SPOT © CNES 2005, distributed bySpot Image ENVISAT ASAR © ESA 2005)

Monitoring long-term surface vertical movements by interferometric SAR near Amsterdam, TheNetherlands, 1993–2000. Red indicates sinking faster than 5 mm per year (Courtesy TerrafirmaProject)

Detection by interferometric space radar of structural damage. The green spots show littlemovement, while the damage is highlighted in blue

ROMANIA - Timis Region Floodings, Spring 2005

Attema 8/1/07 4:51 PM Page 14

resolution have meant so far that SARsystems include different operationalmodes that either optimise the spatialresolution (at the expense of the swathwidth, hence the coverage) or the swathwidth (at the expense of the resolution).GMES will provide access to very high-resolution SAR national missions(Germany’s TerraSAR-X and Italy’sCosmo-SkyMed), so Sentinel-1 isdesigned to address medium-resolutionapplications with its main mode: a wideswath (250 km) and medium resolution(5 x 20 m).

Products for Marine Core ServicesSAR is the primary source of data forinformation on the oceans and theArctic environment. The problems ofaccess to the open oceans and the harshArctic often make radar, with its abilityfor observations in all weather and dayor night, the only reliable informationsource. Typical products for the ice andsnow services include monitoringglaciers and snow, icebergs, sea ice (floeedge) and the near-shore ice complex.

For determining the direction, wave-length and (extreme) heights of waveson the open oceans, SAR imagettes arebeing used in near-realtime inconjunction with global ocean wavemodels. The extensive wave modearchive built up by ERS and Envisat is acritical resource for analysing regionalwave climate and extreme wave events.

ERS-1/2 tandem mission.During the ERS tandemphase, data pairs werecollected on successivedays.

Classifying land coveris not the only importantapplication of SAR toland monitoring. Sincei n t e r f e r o m e t r i c radar can detect surfacemovements to within afew millimetres per year,it is now an establishedtechnique to monitor theeffects of landslides,earthquakes and man-made activities such asbuilding construction,tunnelling, water ornatural gas extraction,and mining.

Products for Emergency ServicesIts all-weather day/night capability makesspace-borne radar the ideal workhorsefor providing information before, duringand after emergencies. Sentinel-1’s two-satellite constellation will routinely revisitall sites within 3 days at the equator andimproving with latitude. In addition, anoptional emergency procedure couldaccelerate access.

Agreements with other satelliteoperators will make daily access or evenbetter a realistic assumption. Thisexcellent revisit performance is feasibleeven while maintaining a spatialresolution of 5 x 20 m. In order toobserve finer detail, regional coverage bysatellites with higher spatial resolution(radar and/or optical) will be required.

Sentinel-1 will build a multi-temporalglobal interferometric image archive thatcan be called on in emergency situations.

SAR is also the primary source ofinformation on oil spills, such assurveillance and drift forecasting, and onship detection for fisheries and security.

Products for Land Monitoring ServicesSAR data are not always the primarysource for basic land-cover classification(forest, agricultural crops, urban areas,etc.) if multi-channel optical imagerywith high spatial resolution is available.However, SAR is commonly used as acomplementary or alternative datasource under adverse atmosphericconditions such as cloud cover.

The contribution made by SAR tobasic land-cover classification wasgreatly increased by the ‘dual polarisa-tion’ mode introduced by Envisat’sASAR. Because the reflective propertiesof a surface depend on the polarisationof the incoming signal, the use of morethan one type of polarisation providesvaluable extra information. This hasbecome a favourite for land classifica-tion. For this reason, Sentinel-1 isdesigned to exploit the full capabilitiesofferred by dual polarisation.

A dramatic improvement is expectedfrom the more frequent revisits to thesame area by Sentinel-1. This featureenhances time-series by adding close todaily sampling. Combined with itsinterferometric capability, Sentinel-1will routinely offer products that wereonly available experimentally from the

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 1514

Sentinel-1

Revisiting a scene only a day later allows interferometry todistinguish between water bodies, forest, urban areas andagriculture. In this single ERS-1/ERS-2 image pair overThe Netherlands, colours are assigned so that generally treesappear green, water appears blue and agricultural fields appearorange

Oil from a wrecked tanker had already reached the northwest coast of Spain whenEnvisat acquired this radar image on 17 November 2002

Map of the flooding in the Timis region of Romania in May 2005, based on Envisat ASAR Narrow Swath and SPOT-5 data. (Image processing and map creation by DLR; SPOT © CNES 2005, distributed bySpot Image ENVISAT ASAR © ESA 2005)

Monitoring long-term surface vertical movements by interferometric SAR near Amsterdam, TheNetherlands, 1993–2000. Red indicates sinking faster than 5 mm per year (Courtesy TerrafirmaProject)

Detection by interferometric space radar of structural damage. The green spots show littlemovement, while the damage is highlighted in blue

ROMANIA - Timis Region Floodings, Spring 2005

Attema 8/1/07 4:51 PM Page 14

– Extra-wide Swath Mode, 400 kmswath and 25 x 100 m spatial resolution(3-looks);

– Wave Mode, low data rate and 5 x 20 mspatial resolution. Sampled images of20 x 20 km at 100 km intervals alongthe orbit.

Data deliveryWith its continuous and conflict-freeoperations, Sentinel-1 will provide ahigh level of service reliability with near-realtime delivery of data within an hourafter reception by the ground station,and with data delivery from archivewithin 24 hours.

PolarisationSentinel-1 has selectable single polarisa-tion (VV or HH) for the Wave Modeand selectable dual polarisation (VV+VH or HH+HV) for all other modes.

Radiometric resolutionFor the end-user of SAR imagery, theradiometric resolution is a criticalparameter becasue it defines the typicalimage noise in radar images caused bythermal noise and speckle. Image noise

be finalised during the project’s initialphase. The satellite is based on thePRIMA (Piattaforma Italiana MultiApplicativa) bus, with a mission-specificpayload module. Experience gainedfrom Canada’s Radarsat-2 and Italy’sCosmo-SkyMed projects, which also usePRIMA, will benefit Sentinel-1.

The design is driven by the payloadrequirements, with particular implica-tions for data transmission and orbitcontrol. The SAR data volume needsrelatively large onboard storagecapacity, and a downlink rate about sixtimes that of Envisat. The X-bandsubsystem design has not yet beenselected, requiring further analysis.

defines how well different surfaces, suchas ice types, agricultural crops and soilmoisture levels, can be classified. Withits extra-wide swath, Sentinel-1 offers30% improvement with respect toEnvisat, while the interferometric wideswath offers a further improvement by afactor of three.

Ground segment and operationsOnce in orbit, Sentinel-1 will beoperated from two centres. ESA’sfacilities in Darmstadt, Germany willcommand the satellite, while missionexploitation will be from Frascati, Italy,including the planning of the SARacquisitions, the processing of theacquired data and the provision of theresulting products to the users. However,the ground segment design and opera-tions concept allow operations to behanded over – partially or fully – toother operating entities in the future.

The satellite operations and missionexploitation present new challenges: thespacecraft needs to work within a tightorbital tube only 100 m in diameter, andmust comply with GMES securityrequirements for command and control.Its operations will be largely automatedduring normal operations but emerg-ency requests have to be accommodatedat short notice.

Exploitation plans need to facilitatesystematic acquisition, reception, pro-cessing, archiving and provision of largeamounts of data to the users. The SARinstrument will be operated in conflict-free sensing modes as much as possible.The ground system must be able tohandle data flows from the satelliteexceeding 1 Terabyte (1012 bytes) per dayand to provide large data volumes withinan hour of reception on the ground.

The operations concept allows thesatellite to operate autonomously andcost-effectively with a 4-day mission planstored onboard, thus allowing automatedoperations over weekends. At the sametime, it is possible to insert individualemergency requests up to 3 hours beforethe planned update of the mission plan tothe satellite. This allows considerableshortening of the response time of

Sentinel-1 compared to its predecessors. An extensive ground segment is

required, with several ground stationsreceiving instrument data at 600 Mbit/s,with cumulative processing capacitiesabove 500 GHz, archiving requirementsexceeding 10 Pentabytes (1015 bytes), andwith data dissemination exceeding currentsystems by an order of magnitude.

In order to fully satisfy the GMESservice requirements, the ground segmentmust include coordinated mission plan-ning and data exchange with othermissions contributing to GMES. Itneeds to guarantee a Quality of Serviceto the user in line with the operationalnature of GMES, ensuring that the dataproducts are accurate, complete andprovided on time.

ConclusionsThe Sentinel-1 constellation is acompletely new approach to SAR missiondesign by ESA in direct response to theoperational needs for SAR data expressedunder the EU-ESA GMES programme.The mission ensures continuity of C-bandSAR data and builds on ESA’s heritageand experience with the ERS and Envisatinstruments, notably maintaining keycharacteristics such as stability andaccurate well-calibrated data products. Atthe same time, mission parameters havebeen vastly improved to meet major userrequirements collected and analysedthrough EU Fast Track and ESA GMESService Element activities, especially inareas such as reliability, revisit time,geographical coverage and rapid datadissemination. As a result, the Sentinel-1pair is expected to provide near-dailycoverage over Europe and Canada,independent of weather with delivery ofradar data within an hour of acquisition –vast improvements over the existing SARsystems.

In addition to responding directly tothe current needs of GMES, the designof the Sentinel-1 mission is expected to enable the development of newapplications and meet the evolving needs of GMES, such as in the area ofclimate change and associatedmonitoring. e

Likewise, the Sentinel-1 requirementsfor operational interferometry placestringent requirements on attitudeaccuracy, attitude and orbit knowledge,and data-take timing accuracy.

Operational modesSentinel-1 has four standard operationalmodes, designed for interoperabilitywith other systems:

– Strip Map Mode, 80 km swath and5 x 5 m spatial resolution;

– Interferometric Wide Swath Mode,250 km swath, 5 x 20 m spatial resolu-tion and burst synchronisation forinterferometry;

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 1716

Sentinel-1

Sentinel-1 Satellite Characteristics

Lifetime: 7 years (consumables 12 years)Launcher: Soyuz from Kourou (baseline),

Zenith-2 (backup)Orbit: near-polar Sun-synchronous

693 km; 12-day repeat cycle; 175 revsper cycle

Mean Local Solar Time: 18:00 atascending node

Orbital period: 98.6 minutesAttitude stabilisation: 3-axis Attitude accuracy: 0.01 deg (each axis)Orbit knowledge: 10 m (each axis,

3-sigma) using GPSOperating autonomy: 96 hoursLaunch mass: 2300 kg (including 130 kg

monopropellant fuel)Size (stowed): 3900 x 2600 x 2500 mmSolar array average power: 4800 W (end-

of-life); battery capacity: >300 AhSpacecraft availability: 0.998Science data storage capacity: 900 Gb

(end-of-life)S-band TT&C data rates: 4 kbit/s

telecommand; 16/128/512 kbit/stelemetry (programmable)

X-band science data rate: 600 Mbit/s

For example, interferometric pairs willmap the effects of earthquakes.

Even with the highly restrictedcoverage of today, C-band SAR is anestablished source of information inemergencies such as flooding and oilspills.

The Sentinel-1 System The Sentinel-1 satellites are being builtby an industrial consortium headed byThales Alenia Space Italy as PrimeContractor, with Astrium Germanyresponsible for the ‘C-SAR’ payload,incorporating the central radarelectronics subsystem developed byAstrium UK. The industrial set-up will

Average revisit time (in days) across the world for the Sentinel-1 constellation oftwo satellites in 12-day repeat orbits with 250 km swath widths. The blue aroundthe equator reflects the 3-day revisit period, improving towards the poles

Attema 8/1/07 4:51 PM Page 16

– Extra-wide Swath Mode, 400 kmswath and 25 x 100 m spatial resolution(3-looks);

– Wave Mode, low data rate and 5 x 20 mspatial resolution. Sampled images of20 x 20 km at 100 km intervals alongthe orbit.

Data deliveryWith its continuous and conflict-freeoperations, Sentinel-1 will provide ahigh level of service reliability with near-realtime delivery of data within an hourafter reception by the ground station,and with data delivery from archivewithin 24 hours.

PolarisationSentinel-1 has selectable single polarisa-tion (VV or HH) for the Wave Modeand selectable dual polarisation (VV+VH or HH+HV) for all other modes.

Radiometric resolutionFor the end-user of SAR imagery, theradiometric resolution is a criticalparameter becasue it defines the typicalimage noise in radar images caused bythermal noise and speckle. Image noise

be finalised during the project’s initialphase. The satellite is based on thePRIMA (Piattaforma Italiana MultiApplicativa) bus, with a mission-specificpayload module. Experience gainedfrom Canada’s Radarsat-2 and Italy’sCosmo-SkyMed projects, which also usePRIMA, will benefit Sentinel-1.

The design is driven by the payloadrequirements, with particular implica-tions for data transmission and orbitcontrol. The SAR data volume needsrelatively large onboard storagecapacity, and a downlink rate about sixtimes that of Envisat. The X-bandsubsystem design has not yet beenselected, requiring further analysis.

defines how well different surfaces, suchas ice types, agricultural crops and soilmoisture levels, can be classified. Withits extra-wide swath, Sentinel-1 offers30% improvement with respect toEnvisat, while the interferometric wideswath offers a further improvement by afactor of three.

Ground segment and operationsOnce in orbit, Sentinel-1 will beoperated from two centres. ESA’sfacilities in Darmstadt, Germany willcommand the satellite, while missionexploitation will be from Frascati, Italy,including the planning of the SARacquisitions, the processing of theacquired data and the provision of theresulting products to the users. However,the ground segment design and opera-tions concept allow operations to behanded over – partially or fully – toother operating entities in the future.

The satellite operations and missionexploitation present new challenges: thespacecraft needs to work within a tightorbital tube only 100 m in diameter, andmust comply with GMES securityrequirements for command and control.Its operations will be largely automatedduring normal operations but emerg-ency requests have to be accommodatedat short notice.

Exploitation plans need to facilitatesystematic acquisition, reception, pro-cessing, archiving and provision of largeamounts of data to the users. The SARinstrument will be operated in conflict-free sensing modes as much as possible.The ground system must be able tohandle data flows from the satelliteexceeding 1 Terabyte (1012 bytes) per dayand to provide large data volumes withinan hour of reception on the ground.

The operations concept allows thesatellite to operate autonomously andcost-effectively with a 4-day mission planstored onboard, thus allowing automatedoperations over weekends. At the sametime, it is possible to insert individualemergency requests up to 3 hours beforethe planned update of the mission plan tothe satellite. This allows considerableshortening of the response time of

Sentinel-1 compared to its predecessors. An extensive ground segment is

required, with several ground stationsreceiving instrument data at 600 Mbit/s,with cumulative processing capacitiesabove 500 GHz, archiving requirementsexceeding 10 Pentabytes (1015 bytes), andwith data dissemination exceeding currentsystems by an order of magnitude.

In order to fully satisfy the GMESservice requirements, the ground segmentmust include coordinated mission plan-ning and data exchange with othermissions contributing to GMES. Itneeds to guarantee a Quality of Serviceto the user in line with the operationalnature of GMES, ensuring that the dataproducts are accurate, complete andprovided on time.

ConclusionsThe Sentinel-1 constellation is acompletely new approach to SAR missiondesign by ESA in direct response to theoperational needs for SAR data expressedunder the EU-ESA GMES programme.The mission ensures continuity of C-bandSAR data and builds on ESA’s heritageand experience with the ERS and Envisatinstruments, notably maintaining keycharacteristics such as stability andaccurate well-calibrated data products. Atthe same time, mission parameters havebeen vastly improved to meet major userrequirements collected and analysedthrough EU Fast Track and ESA GMESService Element activities, especially inareas such as reliability, revisit time,geographical coverage and rapid datadissemination. As a result, the Sentinel-1pair is expected to provide near-dailycoverage over Europe and Canada,independent of weather with delivery ofradar data within an hour of acquisition –vast improvements over the existing SARsystems.

In addition to responding directly tothe current needs of GMES, the designof the Sentinel-1 mission is expected to enable the development of newapplications and meet the evolving needs of GMES, such as in the area ofclimate change and associatedmonitoring. e

Likewise, the Sentinel-1 requirementsfor operational interferometry placestringent requirements on attitudeaccuracy, attitude and orbit knowledge,and data-take timing accuracy.

Operational modesSentinel-1 has four standard operationalmodes, designed for interoperabilitywith other systems:

– Strip Map Mode, 80 km swath and5 x 5 m spatial resolution;

– Interferometric Wide Swath Mode,250 km swath, 5 x 20 m spatial resolu-tion and burst synchronisation forinterferometry;

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 1716

Sentinel-1

Sentinel-1 Satellite Characteristics

Lifetime: 7 years (consumables 12 years)Launcher: Soyuz from Kourou (baseline),

Zenith-2 (backup)Orbit: near-polar Sun-synchronous

693 km; 12-day repeat cycle; 175 revsper cycle

Mean Local Solar Time: 18:00 atascending node

Orbital period: 98.6 minutesAttitude stabilisation: 3-axis Attitude accuracy: 0.01 deg (each axis)Orbit knowledge: 10 m (each axis,

3-sigma) using GPSOperating autonomy: 96 hoursLaunch mass: 2300 kg (including 130 kg

monopropellant fuel)Size (stowed): 3900 x 2600 x 2500 mmSolar array average power: 4800 W (end-

of-life); battery capacity: >300 AhSpacecraft availability: 0.998Science data storage capacity: 900 Gb

(end-of-life)S-band TT&C data rates: 4 kbit/s

telecommand; 16/128/512 kbit/stelemetry (programmable)

X-band science data rate: 600 Mbit/s

For example, interferometric pairs willmap the effects of earthquakes.

Even with the highly restrictedcoverage of today, C-band SAR is anestablished source of information inemergencies such as flooding and oilspills.

The Sentinel-1 System The Sentinel-1 satellites are being builtby an industrial consortium headed byThales Alenia Space Italy as PrimeContractor, with Astrium Germanyresponsible for the ‘C-SAR’ payload,incorporating the central radarelectronics subsystem developed byAstrium UK. The industrial set-up will

Average revisit time (in days) across the world for the Sentinel-1 constellation oftwo satellites in 12-day repeat orbits with 250 km swath widths. The blue aroundthe equator reflects the 3-day revisit period, improving towards the poles

Attema 8/1/07 4:51 PM Page 16

Sentinel-2

The ESA Sentinels will be the first series of

loperational satellites to meet the Earthobservation needs of the European Union-

ESA Global Monitoring for Environment andSecurity (GMES) programme. The pair ofSentinel-2 satellites will routinely provide high-resolution (10–20 m) optical images globallywith frequent revisits tailored to the needs ofGMES land and emergency services. Sentinel-2aims at ensuring continuity of Spot- andLandsat-type data, with improvements toallow service evolution. The first launch isexpected in 2012.

What Users NeedThe pair of Sentinel-2 satellites willroutinely generate valuable informationfor the European Union (EU) and itsMember States as part of the GlobalMonitoring for Environment andSecurity (GMES) programme, in theareas of global climate change (KyotoProtocol and ensuing regulations),sustainable development, Europeanenvironmental policies (such as spatialplanning for the Soil Thematic Strategy,Natura 2000, and the Water FrameworkDirective), risk management, the

Philippe Martimort, Michael Berger,Bernardo Carnicero, Umberto Del Bello,Valérie Fernandez, Ferran Gascon,Pierluigi Silvestrin, François Spoto & Omar Sy Directorate of Earth Observation Programmes,ESTEC, Noordwijk, The Netherlands

Olivier Arino, Roberto Biasutti & Bruno GrecoDirectorate of Earth Observation Programmes,ESRIN, Frascati, Italy

esa bulletin 131 - august 2007 19

Martimort 8/1/07 4:59 PM Page 18

Sentinel-2

The ESA Sentinels will be the first series of

loperational satellites to meet the Earthobservation needs of the European Union-

ESA Global Monitoring for Environment andSecurity (GMES) programme. The pair ofSentinel-2 satellites will routinely provide high-resolution (10–20 m) optical images globallywith frequent revisits tailored to the needs ofGMES land and emergency services. Sentinel-2aims at ensuring continuity of Spot- andLandsat-type data, with improvements toallow service evolution. The first launch isexpected in 2012.

What Users NeedThe pair of Sentinel-2 satellites willroutinely generate valuable informationfor the European Union (EU) and itsMember States as part of the GlobalMonitoring for Environment andSecurity (GMES) programme, in theareas of global climate change (KyotoProtocol and ensuing regulations),sustainable development, Europeanenvironmental policies (such as spatialplanning for the Soil Thematic Strategy,Natura 2000, and the Water FrameworkDirective), risk management, the

Philippe Martimort, Michael Berger,Bernardo Carnicero, Umberto Del Bello,Valérie Fernandez, Ferran Gascon,Pierluigi Silvestrin, François Spoto & Omar Sy Directorate of Earth Observation Programmes,ESTEC, Noordwijk, The Netherlands

Olivier Arino, Roberto Biasutti & Bruno GrecoDirectorate of Earth Observation Programmes,ESRIN, Frascati, Italy

esa bulletin 131 - august 2007 19

Martimort 8/1/07 4:59 PM Page 18

Common Agricultural Policy, develop-ment and humanitarian aid, andcommon foreign and security policy.

To meet these needs, Sentinel-2 datawill underpin the routine generation ofproducts such as: generic land-cover,land-use and change maps, and riskmapping and fast images for disasterrelief. They will also evolve towards thegeneration of geophysical variables likeleaf coverage, leaf chlorophyll contentand leaf water content.

GMES will use Sentinel-2 along withwith other optical satellites to providecomplete observations. Conversely,Sentinel-2 will be a member of the land-surface imaging constellation of theinternational Committee on EarthObservation Satellites (CEOS), who willcoordinate access to the missions of thesame type (especially for Landsat data-continuity) to improve the finalinformation for users. Sentinel-2 willensure European independence whilecontributing to the global push forimproved land imaging.

These goals have driven the designtowards a dependable multispectralEarth-observation system that ensurescontinuity for Landsat and Spot obser-vations and improves data availabilityfor users. That, in turn, has identifiedpriority improvements over pastsatellites.

Geographic coverageThe mission is dedicated to the full andsystematic coverage of land surfaces(including major islands) from 56ºS(southern Americas) to +83ºN (northernGreenland), providing cloud-free productsevery 15–30 days. To achieve this and forreliability, a constellation of two opera-tional satellites is required, yielding5 days between revisits. At thebeginning, with only one satellite, thegap is 10 days (although opticalinstruments on other GMES satelliteswill help to fill the gaps).

Additionally, some limited geograph-ical areas will be reachable within1–3 days in emergencies such as floodsand earthquakes by rolling and tiltingthe satellite.

By comparison, the US Landsat-7 has16-day revisits and Spot 26-day revisits,and neither provides systematic coverageof land.

In order to support operationalservices for at least 15 years from thelaunch of the first satellites, a series offour satellites is planned, with twooperating in orbit and a third in groundstorage as backup.

Spectral coverageThe Multi-Spectral Instrument (MSI)features 13 spectral bands from thevisible and near-infrared (VNIR) to theshort-wave infrared (SWIR), featuringfour at 10 m, six at 20 m and three at60 m resolution. The best compromisein terms of user requirements andmission performance, cost and schedulerisk, it provides enhanced continuity forSpot and Landsat, with narrower bandsfor improving identification of features,additional red channels for assessingvegetation, and dedicated bands forimproving atmospheric correction anddetecting cirrus clouds.

Processing and distributionAfter reception, the data will beprocessed systematically over predefinedareas in predefined time windows,selected by user requests. The data willthen be made available to users whohave notified their interest in thatparticular set. Dissemination will beperformed mostly online. This avoidsindividual ordering. It is made possibleby the largely repetitive geographicalcoverage that can dispense with day-to-day mission planning. However, on-demand production and delivery will beprovided for important specific caseslike disaster management. Missionplanning is required only for the roll-tiltmanoeuvre in these unpredictable cases.

Mission DescriptionFrequent revisits and high missionavailability require two Sentinelsoperating simultaneously, which dictatesa small, cost-effective and low-risksatellite. The orbit is Sun-synchronousat 786 km altitude (14+3/10 revolutions

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 2120

Sentinel-2

leaf area

leaf chlorophyll content

fractional vegetation cover

leaf water content

Revisit time (in days) in summer with two satellites

Four typical products extracted from a simulatedSentinel-2 image (top). Different combinations ofwavelengths reveal different features in the landscape

Sentinel-2’s camera works in 13 windows(wavelength along the bottom) at three resolutions(shown at left)

Martimort 8/1/07 4:59 PM Page 20

Common Agricultural Policy, develop-ment and humanitarian aid, andcommon foreign and security policy.

To meet these needs, Sentinel-2 datawill underpin the routine generation ofproducts such as: generic land-cover,land-use and change maps, and riskmapping and fast images for disasterrelief. They will also evolve towards thegeneration of geophysical variables likeleaf coverage, leaf chlorophyll contentand leaf water content.

GMES will use Sentinel-2 along withwith other optical satellites to providecomplete observations. Conversely,Sentinel-2 will be a member of the land-surface imaging constellation of theinternational Committee on EarthObservation Satellites (CEOS), who willcoordinate access to the missions of thesame type (especially for Landsat data-continuity) to improve the finalinformation for users. Sentinel-2 willensure European independence whilecontributing to the global push forimproved land imaging.

These goals have driven the designtowards a dependable multispectralEarth-observation system that ensurescontinuity for Landsat and Spot obser-vations and improves data availabilityfor users. That, in turn, has identifiedpriority improvements over pastsatellites.

Geographic coverageThe mission is dedicated to the full andsystematic coverage of land surfaces(including major islands) from 56ºS(southern Americas) to +83ºN (northernGreenland), providing cloud-free productsevery 15–30 days. To achieve this and forreliability, a constellation of two opera-tional satellites is required, yielding5 days between revisits. At thebeginning, with only one satellite, thegap is 10 days (although opticalinstruments on other GMES satelliteswill help to fill the gaps).

Additionally, some limited geograph-ical areas will be reachable within1–3 days in emergencies such as floodsand earthquakes by rolling and tiltingthe satellite.

By comparison, the US Landsat-7 has16-day revisits and Spot 26-day revisits,and neither provides systematic coverageof land.

In order to support operationalservices for at least 15 years from thelaunch of the first satellites, a series offour satellites is planned, with twooperating in orbit and a third in groundstorage as backup.

Spectral coverageThe Multi-Spectral Instrument (MSI)features 13 spectral bands from thevisible and near-infrared (VNIR) to theshort-wave infrared (SWIR), featuringfour at 10 m, six at 20 m and three at60 m resolution. The best compromisein terms of user requirements andmission performance, cost and schedulerisk, it provides enhanced continuity forSpot and Landsat, with narrower bandsfor improving identification of features,additional red channels for assessingvegetation, and dedicated bands forimproving atmospheric correction anddetecting cirrus clouds.

Processing and distributionAfter reception, the data will beprocessed systematically over predefinedareas in predefined time windows,selected by user requests. The data willthen be made available to users whohave notified their interest in thatparticular set. Dissemination will beperformed mostly online. This avoidsindividual ordering. It is made possibleby the largely repetitive geographicalcoverage that can dispense with day-to-day mission planning. However, on-demand production and delivery will beprovided for important specific caseslike disaster management. Missionplanning is required only for the roll-tiltmanoeuvre in these unpredictable cases.

Mission DescriptionFrequent revisits and high missionavailability require two Sentinelsoperating simultaneously, which dictatesa small, cost-effective and low-risksatellite. The orbit is Sun-synchronousat 786 km altitude (14+3/10 revolutions

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 2120

Sentinel-2

leaf area

leaf chlorophyll content

fractional vegetation cover

leaf water content

Revisit time (in days) in summer with two satellites

Four typical products extracted from a simulatedSentinel-2 image (top). Different combinations ofwavelengths reveal different features in the landscape

Sentinel-2’s camera works in 13 windows(wavelength along the bottom) at three resolutions(shown at left)

Martimort 8/1/07 4:59 PM Page 20

per day) with a 10:30 a.m. descendingnode. This local time is the bestcompromise between minimising cloudcover and ensuring suitable Sunillumination. It is close to the Landsatlocal time and matches Spot’s, allowingthe seamless combination of Sentinel-2data with historical images to buildlong-term time series. The two satelliteswill work on opposite sides of the orbit.

The ground station network mustprovide long contact times in order todownlink all the observations; at leastfour core stations are required. Onepolar station for telemetry, tracking andcontrol is sufficient. To a limited extent,the system will also allow directreception by local user stations for near-realtime applications.

The SatellitesA compact 1 t satellite will be launchedon ESA’s Vega (baseline, with Rockot asbackup). The satellite is designed for a

filter assemblies are being developedbefore the main project begins. Each pre-development involves two manufacturersto reduce risks, foster competition andmeet ESA’s geographical return require-ments for the main phase.

Ground segmentThe ground segment includes a FlightOperations Segment for commandingthe satellite, and a decentralised PayloadData Ground Segment, an evolvingmulti-mission infrastructure for missionplanning, data reception, processing,archiving, quality control and dissemin-ation.

7-year lifetime, with propellant for12 years of operations, including de-orbiting at the end. The roof-shapedconfiguration with a fixed body-mounted solar array as defined inPhase-A/B1 leads to a simple mechani-cal design, without solar array deploy-ment or drive mechanisms. The satelliteis controlled in 3-axes via high-ratemulti-head startrackers, mounted on thecamera structure for better pointingaccuracy and stability, and gyroscopesand a satnav receiver. Power comes fromhigh-efficiency gallium arsenide triple-junction solar cells and a lithium-ionbattery. The satellite is tilted at 22.5º toits roll axis to maximise the illuminationof its solar array.

Images are stored in a 2 Tbit solid-state mass memory before down-linking at 450 Mbit/s in the X-band.Command and control is performedthrough an omni-directional S-bandantenna.

The users in the dispersed ServiceSegment will take data from differentsatellites in combination with non-spacedata to deliver customised services tothe final users.

Sentinel-2 will be a key Europeansource of data for the GMES LandFast-Track Monitoring Services and willcontribute to the GMES Risk Fast-Track Services. It will provide continuityof data to ESA’s GMES Service Elementprojects such as forestry (GSE ForestMonitoring), soil and water resourcesmapping, urban mapping and classifica-tion (SAGE, Urban Services, Coast-watch, GSE Land, RISK-EOS).

ConclusionThe Sentinel-2 wide-swath high-resolu-tion multispectral system will provideimproved continuity for Spot- andLandsat-type observations, with improvedrevisit time, coverage area, spectralbands, swath width, and radiometricand geometric image quality, meetingGMES needs for operational land andemergency services.

The Sentinel-2 Definition Phase-A/B1was performed by ESA in 2005 and 2006with an industrial consortium led byAstrium GmbH (mission prime, platform,system engineering), with Astrium SAS asthe major subcontractor (payload, systemsupport). Following the completion ofthis phase in January 2007, the Invitationto Tender for the Implementation Phasewas released in February 2007. ThisPhase-B2/C/D/E1 is expected to start inOctober 2007, with launch of the firstsatellite projected for 2012. e

Multispectral instrumentMSI features a three-mirror anastigmattelescope with a pupil diameter of about150 mm; it is the key to the high imagequality across the wide field of view of290 km (Landsat 185 km, Spot 120 km).The telescope structure and mirrors aremade of silicon carbide to minimisethermal deformation.

The VNIR focal plane employs mono-lithic CMOS (complementary metaloxide semiconductor) detectors, whilethe SWIR uses a mercury-cadmium-telluride detector hybridised on aCMOS read-out circuit. A dichroicbeam-splitter separates the VNIR andSWIR channels. A combination ofpartial onboard calibration, using a Sundiffuser, and calibration with groundtargets will guarantee high radiometricperformance.

The detector signals are digitised athigh resolution (12-bit), and state-of-the-art lossy data compression reducesthe data volume. The compression ratiowill be fine-tuned for each spectral bandto ensure that there is no significanteffect on image quality.

A shutter prevents direct viewing ofthe Sun in orbit and contaminationduring launch. The average observationtime per orbit is 16.3 minutes, with apeak value of 31 minutes.

In order to mitigate the developmentrisks and secure the developmentschedule, the technologies for building thecritical VNIR and SWIR detectors and

Earth Observation

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Sentinel-2

The complex light path within the camera allows a more compactinstrument. FPA is the Focal Plane Assembly.

Simulated Sentinel-2 colour composite images using thered/green/blue bands (above) and near-infrared/red/green(below)

Sentinel-2’s multispectral camera

Secondary mirror

Fold mirror

VNIR/Pan FPA

Primary mirror

Tertiary mirror

Dichroic and compensator

SWIR FPA

An example of how the multispectral images fromAn example of how the multispectral images fromSentinelSentinel -- 2 will be analysed to reveal land-use2 will be analysed to reveal land-use

Martimort 8/1/07 4:59 PM Page 22

per day) with a 10:30 a.m. descendingnode. This local time is the bestcompromise between minimising cloudcover and ensuring suitable Sunillumination. It is close to the Landsatlocal time and matches Spot’s, allowingthe seamless combination of Sentinel-2data with historical images to buildlong-term time series. The two satelliteswill work on opposite sides of the orbit.

The ground station network mustprovide long contact times in order todownlink all the observations; at leastfour core stations are required. Onepolar station for telemetry, tracking andcontrol is sufficient. To a limited extent,the system will also allow directreception by local user stations for near-realtime applications.

The SatellitesA compact 1 t satellite will be launchedon ESA’s Vega (baseline, with Rockot asbackup). The satellite is designed for a

filter assemblies are being developedbefore the main project begins. Each pre-development involves two manufacturersto reduce risks, foster competition andmeet ESA’s geographical return require-ments for the main phase.

Ground segmentThe ground segment includes a FlightOperations Segment for commandingthe satellite, and a decentralised PayloadData Ground Segment, an evolvingmulti-mission infrastructure for missionplanning, data reception, processing,archiving, quality control and dissemin-ation.

7-year lifetime, with propellant for12 years of operations, including de-orbiting at the end. The roof-shapedconfiguration with a fixed body-mounted solar array as defined inPhase-A/B1 leads to a simple mechani-cal design, without solar array deploy-ment or drive mechanisms. The satelliteis controlled in 3-axes via high-ratemulti-head startrackers, mounted on thecamera structure for better pointingaccuracy and stability, and gyroscopesand a satnav receiver. Power comes fromhigh-efficiency gallium arsenide triple-junction solar cells and a lithium-ionbattery. The satellite is tilted at 22.5º toits roll axis to maximise the illuminationof its solar array.

Images are stored in a 2 Tbit solid-state mass memory before down-linking at 450 Mbit/s in the X-band.Command and control is performedthrough an omni-directional S-bandantenna.

The users in the dispersed ServiceSegment will take data from differentsatellites in combination with non-spacedata to deliver customised services tothe final users.

Sentinel-2 will be a key Europeansource of data for the GMES LandFast-Track Monitoring Services and willcontribute to the GMES Risk Fast-Track Services. It will provide continuityof data to ESA’s GMES Service Elementprojects such as forestry (GSE ForestMonitoring), soil and water resourcesmapping, urban mapping and classifica-tion (SAGE, Urban Services, Coast-watch, GSE Land, RISK-EOS).

ConclusionThe Sentinel-2 wide-swath high-resolu-tion multispectral system will provideimproved continuity for Spot- andLandsat-type observations, with improvedrevisit time, coverage area, spectralbands, swath width, and radiometricand geometric image quality, meetingGMES needs for operational land andemergency services.

The Sentinel-2 Definition Phase-A/B1was performed by ESA in 2005 and 2006with an industrial consortium led byAstrium GmbH (mission prime, platform,system engineering), with Astrium SAS asthe major subcontractor (payload, systemsupport). Following the completion ofthis phase in January 2007, the Invitationto Tender for the Implementation Phasewas released in February 2007. ThisPhase-B2/C/D/E1 is expected to start inOctober 2007, with launch of the firstsatellite projected for 2012. e

Multispectral instrumentMSI features a three-mirror anastigmattelescope with a pupil diameter of about150 mm; it is the key to the high imagequality across the wide field of view of290 km (Landsat 185 km, Spot 120 km).The telescope structure and mirrors aremade of silicon carbide to minimisethermal deformation.

The VNIR focal plane employs mono-lithic CMOS (complementary metaloxide semiconductor) detectors, whilethe SWIR uses a mercury-cadmium-telluride detector hybridised on aCMOS read-out circuit. A dichroicbeam-splitter separates the VNIR andSWIR channels. A combination ofpartial onboard calibration, using a Sundiffuser, and calibration with groundtargets will guarantee high radiometricperformance.

The detector signals are digitised athigh resolution (12-bit), and state-of-the-art lossy data compression reducesthe data volume. The compression ratiowill be fine-tuned for each spectral bandto ensure that there is no significanteffect on image quality.

A shutter prevents direct viewing ofthe Sun in orbit and contaminationduring launch. The average observationtime per orbit is 16.3 minutes, with apeak value of 31 minutes.

In order to mitigate the developmentrisks and secure the developmentschedule, the technologies for building thecritical VNIR and SWIR detectors and

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 2322

Sentinel-2

The complex light path within the camera allows a more compactinstrument. FPA is the Focal Plane Assembly.

Simulated Sentinel-2 colour composite images using thered/green/blue bands (above) and near-infrared/red/green(below)

Sentinel-2’s multispectral camera

Secondary mirror

Fold mirror

VNIR/Pan FPA

Primary mirror

Tertiary mirror

Dichroic and compensator

SWIR FPA

An example of how the multispectral images fromAn example of how the multispectral images fromSentinelSentinel -- 2 will be analysed to reveal land-use2 will be analysed to reveal land-use

Martimort 8/1/07 4:59 PM Page 22

Sentinel-3

The ESA Sentinels will be the first series of

noperational satellites to meet the Earthlobservation needs of the European Union-

ESA Global Monitoring for Environment andSecurity (GMES) programme. The pair ofSentinel-3 satellites will provide global,frequent and near-realtime ocean, ice and landmonitoring. It continues Envisat’s altimetry, themultispectral, medium-resolution visible andinfrared ocean and land-surface observations ofERS, Envisat and Spot, and includes enhance-ments to meet the operational revisit require-ments and to facilitate new products andevolution of services. The first launch isexpected in 2011/2012.

What Users NeedThe pair of Sentinel-3 satellites willroutinely monitor ocean and landsurfaces to generate valuable informa-tion for the European Union (EU) andits Member States as part of the GlobalMonitoring for Environment andSecurity (GMES) programme (www.gmes.info). The EU Marine Core Service(MCS) and the Land Monitoring CoreService (LMCS), together with the ESAGMES Service Element (GSE), have

Miguel Aguirre, Bruno Berruti, Jean-Loup Bezy,Mark Drinkwater, Florence Heliere, Ulf Klein,Constantinos Mavrocordatos & Pierluigi Silvestrin Directorate of Earth Observation Programmes,ESTEC, Noordwijk, The Netherlands

Bruno Greco & Jerome BenvenisteDirectorate of Earth Observation Programmes,ESRIN, Frascati, Italy

esa bulletin 131 - august 2007 25

Sentinel-3 The Ocean and Medium-Resolution Land

Mission for GMES Operational Services

Sentinel-3 will continue the images providedby Envisat’s MERIS instrument

Aguirre 8/1/07 5:01 PM Page 24

Sentinel-3

The ESA Sentinels will be the first series of

noperational satellites to meet the Earthlobservation needs of the European Union-

ESA Global Monitoring for Environment andSecurity (GMES) programme. The pair ofSentinel-3 satellites will provide global,frequent and near-realtime ocean, ice and landmonitoring. It continues Envisat’s altimetry, themultispectral, medium-resolution visible andinfrared ocean and land-surface observations ofERS, Envisat and Spot, and includes enhance-ments to meet the operational revisit require-ments and to facilitate new products andevolution of services. The first launch isexpected in 2011/2012.

What Users NeedThe pair of Sentinel-3 satellites willroutinely monitor ocean and landsurfaces to generate valuable informa-tion for the European Union (EU) andits Member States as part of the GlobalMonitoring for Environment andSecurity (GMES) programme (www.gmes.info). The EU Marine Core Service(MCS) and the Land Monitoring CoreService (LMCS), together with the ESAGMES Service Element (GSE), have

Miguel Aguirre, Bruno Berruti, Jean-Loup Bezy,Mark Drinkwater, Florence Heliere, Ulf Klein,Constantinos Mavrocordatos & Pierluigi Silvestrin Directorate of Earth Observation Programmes,ESTEC, Noordwijk, The Netherlands

Bruno Greco & Jerome BenvenisteDirectorate of Earth Observation Programmes,ESRIN, Frascati, Italy

esa bulletin 131 - august 2007 25

Sentinel-3 The Ocean and Medium-Resolution Land

Mission for GMES Operational Services

Sentinel-3 will continue the images providedby Envisat’s MERIS instrument

Aguirre 8/1/07 5:01 PM Page 24

been consolidating those services wherecontinuity and success depends onoperational data flowing from theSentinels.

For MCS, operational oceanographyservices are being developed within theMERSEA 6th Framework Programme(w3.mersea.eu.org) and through the ESAGSE Marcoast (gmes-marcoast.com)and Polarview (www.polarview.org)projects. The MCS will deliver regular,

general suite of high-level geophysicalproducts, with priority on:– ocean, ice, land and inland water

surface topography;– sea-surface temperature;– ocean colour;– land surface biophysical properties;– land surface temperature.

These primary goals have driven thedesign towards a mission concept thatcan routinely and continuously (that is,operationally) deliver robust productswith well-characterised accuracy andconfidence limits. In turn, this will leadto improvements over previous missionsand instruments, which, through theirtechnology and data-processing, haveguided the design of the Sentinel-3system.

Mission DefinitionThe sea-surface topography mission hasthe primary objective of providingaccurate, closely spaced altimetrymeasurements from a high-inclinationorbit with a long repeat cycle, tocomplement the Jason ocean altimeterseries. Monitoring mid-scale circulationand sea levels requires measurement ofocean topography. Measuring waveheights is essential for operational waveforecasting. Sea-ice measurementssimilar to those from CryoSat-2 (thoughfrom a slightly different orbit) will bemade. The single-antenna radar altimeter,with aperture synthesis processing forincreased along-track resolution,balances the needs for continuity andimproved performance. It will extendobservations to inland waters andcoastal zones.

Accompanying the altimeter will be aPrecise Orbit Determination (POD)system and microwave radiometer(MWR) for removing the errors addedas the signals are delayed by watervapour in the atmosphere. The altimeterwill track over a variety of surfaces:open ocean, coastal sea zones, sea iceand inland waters. The chosen mode willdepend on the surface below, withchanges pre-programmed in the satelliteto avoid data loss.

systematic products on sea-surfacetopography and sea-state and ecosystemcharacteristics over the oceans and theEuropean regional and shelf seas. Theinformation from Sentinel-3 will beassimilated into models in near-realtimeto provide routinely the best-availableestimate of the state of the oceans,together with forecasts (from days toweeks) and reanalyses (‘hindcasts’ ofocean state over long time-series in the

The Ocean and Land Colour Instru-ment (OLCI), based on Envisat’sMERIS instrument, fulfils ocean colourand land-cover objectives. The Sea andLand Surface Temperature Radiometer(SLSTR), based on Envisat’s AdvancedAlong Track Scanning Radiometer(AATSR), is designed for ocean andland-surface temperature observations.Unlike AATSR, SLSTR has a double-scanning mechanism, yielding a muchwider swath stretching almost fromhorizon to horizon. The OLCI andSLSTR swaths will broadly overlap,yielding extra information.

The Sun-synchronous orbit chosen isat 814 km altitude (14+7/27 revolutionsper day) with a local equatorial crossingtime of 10:00 a.m., as a compromise

between the needs of the optical instru-ment and altimeter. The baseline of twosatellites supports full imaging of theoceans within 2 days (even allowing forimages spoiled by the Sun glinting offthe water), while delivering global landcoverage in just over a day at the equatorand improving with latitude.

The continuous acquisitions ofSentinel-3 allow routine operations. Anaverage of 103 Gbit of data will bedownlinked once per orbit at 300 Mbit/sX-band to a single ground station withno blind orbits.

Four categories of products will bedelivered: ocean colour, surface topo-graphy, surface temperature (land andsea) and land. The surface topographyproducts will be delivered with threetimeliness levels: NRT (Near-Real Time,3 hours), STC (Standard Time Critical,1–2 days) and NTC (Non-Time Critical,1 month). Slower products allow moreaccurate processing and better quality.NRT products are ingested intonumerical weather prediction and sea-state prediction models for quick, short-term forecasts. STC products are ingestedinto ocean models for accurate presentstate estimates and forecasts. NTCproducts are used in all high-precisionclimatological applications, such as sea-level estimates. The resulting analyses

past). The fast-track component of theMCS focuses on ocean dynamics andprimary ecosystem characteristics, butalso covers sea-ice monitoring and oil-spill detection.

The Land Monitoring Core Service isbeing developed through the Geoland6th Framework Programme (www.gmes-geoland.info) and ESA GSE projectssuch as Forest Monitoring (www.gmes-forest.info), Global Monitoring forFood Security (www.gmfs.info), and thedisaster mitigation and humanitarianrelief RESPOND (www.respond-int.org)service.

LMCS focuses on exhaustive high-resolution continental-scale land-cover/land-use mapping complemented byland-monitoring based on daily land-cover mapping, vegetation character-istics and fire monitoring at continentaland global scales. The dynamics ofvegetation characteristics require anupdate frequency of days to weeks, andcomprehensive global observations withthe best revisit frequency possible(especially to minimise the effects ofclouds and high levels of aerosols).

LMCS will evolve in Europe toinclude vegetation monitoring linked toCommon Agricultural Policy require-ments such as reviewing and monitoringEU policies (water framework directive,biodiversity strategy, common agricul-tural, regional policies) and reportingobligations under international treatiessuch as the Kyoto Protocol.

Sentinel-3 will frequently revisit allsites. This is useful, for example, for cropyield monitoring and food security, andforest cover mapping and changemonitoring. Parameters include landcover, leaf area index, fraction ofabsorbed photosynthetically activeradiation, burnt areas, and land surfaceand active fire temperature. These globalvegetation data, together with atmo-spheric corrections, such as aerosoloptical depth, will provide critical inputdata for numerical weather forecasting,global climate models and in climateand greenhouse gas monitoring.

To meet user needs, Sentinel-3 willsupport the routine generation of a

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 2726

Sentinel-3

Marine and Coastal EnvironmentSea-surface topographyMesoscale circulationWater qualitySea-surface temperatureWave height and wind speedSediment load and transportEutrophication (excessive plant growth in

water bodies)

Polar Environment Sea-ice thickness Ice surface temperature

Maritime SecurityOcean-current forecastingWater transparency Wind and wave height

Global Change OceanGlobal sea-level riseGlobal ocean warmingOcean carbon dioxide flux

Land Cover & Land-Use ChangeLand-use mapping Vegetation indices

Forest MonitoringForest cover mapping

Food Security Early WarningRegional land-cover mappingDrought monitoring

Humanitarian AidLand-use mapping

Air Pollution (local to regional scales)Aerosol concentration

Risk Management (flood and fires)Burned scar mappingFire detection

Global Change LandForest-cover change mappingSoil degradation mapping

GMES/Sentinel-3 Initial Services Sentinel-3 will deliver routine operational services to policy-makers and marine and landservice users:

Sentinel-3 in launch configuration

OLCI is pointed eastwards, away from the Sun, to minimise Sun-glint off the sea. SLSTR has a symmetric double-scanning geometry,producing two swaths. The wide swath totally covers the OLCI swath for product synergy. The narrow-swath data, corrected withinformation from the wide swath, provides nadir-centred high-accuracy sea-surface temperature

MWR

SLSTR swath with single view

SLSTR swath with single view

Longitude (deg)

Lo

ng

itu

de

(d

eg

)

SLSTR

sampling geometry

(in blue)

OLCI swath

OLCI

sampling geometry

OLCI

SLSTR

LRR

RA

Aguirre 8/1/07 5:01 PM Page 26

been consolidating those services wherecontinuity and success depends onoperational data flowing from theSentinels.

For MCS, operational oceanographyservices are being developed within theMERSEA 6th Framework Programme(w3.mersea.eu.org) and through the ESAGSE Marcoast (gmes-marcoast.com)and Polarview (www.polarview.org)projects. The MCS will deliver regular,

general suite of high-level geophysicalproducts, with priority on:– ocean, ice, land and inland water

surface topography;– sea-surface temperature;– ocean colour;– land surface biophysical properties;– land surface temperature.

These primary goals have driven thedesign towards a mission concept thatcan routinely and continuously (that is,operationally) deliver robust productswith well-characterised accuracy andconfidence limits. In turn, this will leadto improvements over previous missionsand instruments, which, through theirtechnology and data-processing, haveguided the design of the Sentinel-3system.

Mission DefinitionThe sea-surface topography mission hasthe primary objective of providingaccurate, closely spaced altimetrymeasurements from a high-inclinationorbit with a long repeat cycle, tocomplement the Jason ocean altimeterseries. Monitoring mid-scale circulationand sea levels requires measurement ofocean topography. Measuring waveheights is essential for operational waveforecasting. Sea-ice measurementssimilar to those from CryoSat-2 (thoughfrom a slightly different orbit) will bemade. The single-antenna radar altimeter,with aperture synthesis processing forincreased along-track resolution,balances the needs for continuity andimproved performance. It will extendobservations to inland waters andcoastal zones.

Accompanying the altimeter will be aPrecise Orbit Determination (POD)system and microwave radiometer(MWR) for removing the errors addedas the signals are delayed by watervapour in the atmosphere. The altimeterwill track over a variety of surfaces:open ocean, coastal sea zones, sea iceand inland waters. The chosen mode willdepend on the surface below, withchanges pre-programmed in the satelliteto avoid data loss.

systematic products on sea-surfacetopography and sea-state and ecosystemcharacteristics over the oceans and theEuropean regional and shelf seas. Theinformation from Sentinel-3 will beassimilated into models in near-realtimeto provide routinely the best-availableestimate of the state of the oceans,together with forecasts (from days toweeks) and reanalyses (‘hindcasts’ ofocean state over long time-series in the

The Ocean and Land Colour Instru-ment (OLCI), based on Envisat’sMERIS instrument, fulfils ocean colourand land-cover objectives. The Sea andLand Surface Temperature Radiometer(SLSTR), based on Envisat’s AdvancedAlong Track Scanning Radiometer(AATSR), is designed for ocean andland-surface temperature observations.Unlike AATSR, SLSTR has a double-scanning mechanism, yielding a muchwider swath stretching almost fromhorizon to horizon. The OLCI andSLSTR swaths will broadly overlap,yielding extra information.

The Sun-synchronous orbit chosen isat 814 km altitude (14+7/27 revolutionsper day) with a local equatorial crossingtime of 10:00 a.m., as a compromise

between the needs of the optical instru-ment and altimeter. The baseline of twosatellites supports full imaging of theoceans within 2 days (even allowing forimages spoiled by the Sun glinting offthe water), while delivering global landcoverage in just over a day at the equatorand improving with latitude.

The continuous acquisitions ofSentinel-3 allow routine operations. Anaverage of 103 Gbit of data will bedownlinked once per orbit at 300 Mbit/sX-band to a single ground station withno blind orbits.

Four categories of products will bedelivered: ocean colour, surface topo-graphy, surface temperature (land andsea) and land. The surface topographyproducts will be delivered with threetimeliness levels: NRT (Near-Real Time,3 hours), STC (Standard Time Critical,1–2 days) and NTC (Non-Time Critical,1 month). Slower products allow moreaccurate processing and better quality.NRT products are ingested intonumerical weather prediction and sea-state prediction models for quick, short-term forecasts. STC products are ingestedinto ocean models for accurate presentstate estimates and forecasts. NTCproducts are used in all high-precisionclimatological applications, such as sea-level estimates. The resulting analyses

past). The fast-track component of theMCS focuses on ocean dynamics andprimary ecosystem characteristics, butalso covers sea-ice monitoring and oil-spill detection.

The Land Monitoring Core Service isbeing developed through the Geoland6th Framework Programme (www.gmes-geoland.info) and ESA GSE projectssuch as Forest Monitoring (www.gmes-forest.info), Global Monitoring forFood Security (www.gmfs.info), and thedisaster mitigation and humanitarianrelief RESPOND (www.respond-int.org)service.

LMCS focuses on exhaustive high-resolution continental-scale land-cover/land-use mapping complemented byland-monitoring based on daily land-cover mapping, vegetation character-istics and fire monitoring at continentaland global scales. The dynamics ofvegetation characteristics require anupdate frequency of days to weeks, andcomprehensive global observations withthe best revisit frequency possible(especially to minimise the effects ofclouds and high levels of aerosols).

LMCS will evolve in Europe toinclude vegetation monitoring linked toCommon Agricultural Policy require-ments such as reviewing and monitoringEU policies (water framework directive,biodiversity strategy, common agricul-tural, regional policies) and reportingobligations under international treatiessuch as the Kyoto Protocol.

Sentinel-3 will frequently revisit allsites. This is useful, for example, for cropyield monitoring and food security, andforest cover mapping and changemonitoring. Parameters include landcover, leaf area index, fraction ofabsorbed photosynthetically activeradiation, burnt areas, and land surfaceand active fire temperature. These globalvegetation data, together with atmo-spheric corrections, such as aerosoloptical depth, will provide critical inputdata for numerical weather forecasting,global climate models and in climateand greenhouse gas monitoring.

To meet user needs, Sentinel-3 willsupport the routine generation of a

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 2726

Sentinel-3

Marine and Coastal EnvironmentSea-surface topographyMesoscale circulationWater qualitySea-surface temperatureWave height and wind speedSediment load and transportEutrophication (excessive plant growth in

water bodies)

Polar Environment Sea-ice thickness Ice surface temperature

Maritime SecurityOcean-current forecastingWater transparency Wind and wave height

Global Change OceanGlobal sea-level riseGlobal ocean warmingOcean carbon dioxide flux

Land Cover & Land-Use ChangeLand-use mapping Vegetation indices

Forest MonitoringForest cover mapping

Food Security Early WarningRegional land-cover mappingDrought monitoring

Humanitarian AidLand-use mapping

Air Pollution (local to regional scales)Aerosol concentration

Risk Management (flood and fires)Burned scar mappingFire detection

Global Change LandForest-cover change mappingSoil degradation mapping

GMES/Sentinel-3 Initial Services Sentinel-3 will deliver routine operational services to policy-makers and marine and landservice users:

Sentinel-3 in launch configuration

OLCI is pointed eastwards, away from the Sun, to minimise Sun-glint off the sea. SLSTR has a symmetric double-scanning geometry,producing two swaths. The wide swath totally covers the OLCI swath for product synergy. The narrow-swath data, corrected withinformation from the wide swath, provides nadir-centred high-accuracy sea-surface temperature

MWR

SLSTR swath with single view

SLSTR swath with single view

Longitude (deg)

Lo

ng

itu

de

(d

eg

)

SLSTR

sampling geometry

(in blue)

OLCI swath

OLCI

sampling geometry

OLCI

SLSTR

LRR

RA

Aguirre 8/1/07 5:01 PM Page 26

and forecast products and predictionsfrom ocean and atmosphere adding datafrom other missions and in situobservations, are the key productsdelivered to users. They provide a robust basis for downstream value-addedproducts and specialised user services.

Satellite Configuration Though carrying five instruments,Sentinel-3 is of moderate size – about1.3 t, 3.9 m high and compatible withsmall launchers like Vega (baseline) andDnepr-ST3 (back-up). It is designed fora 7-year lifetime, with 90 kg of hydrazinepropellant for 12 years of operations,including deorbiting at the end.

The layout is driven by the need toprovide a large anti-Sun side to cool theoptical instruments.

Optical instrumentsThe two optical instruments, OLCI andSLSTR, will provide a common quasi-simultaneous view of the Earth to helpdevelop synergetic products.

The 150 kg OLCI benefits fromMERIS heritage. The field-of-view isdivided between five cameras on acommon structure with the calibrationassembly. Each camera has an opticalgrating to provide the minimum baselineof 16 spectral bands required by themission together with the potential foroptional bands for improved atmo-spheric corrections.

OLCI is an autonomous instrumentwith simple interfaces to the satellite,thus allowing easy integration andminimising development risks.

topography like ice margins. In thismode, SRAL’s tracking window iscontrolled based on a priori knowledgeof the surface height, from existinghigh-resolution global digital elevationmodels, combined with knowledge ofthe location of the satellite from thesatnav receiver. The main advantage isthat the measurements are continuous,avoiding the data gaps typical of closed-

The 90 kg visible/infrared SLSTRmeasures sea- and land-surface temp-eratures, following the AATSR concept.Its rotary scan mirror mechanismproduces the wide swath of 750 km. Itfeatures ~1 km resolution at nadir forthermal-infrared channels and 500 mfor visible and shortwave infraredchannels. Like AATSR, it offers dualviews – inclined forward and near-vertical nadir – to provide robustatmospheric correction over the swath.The nadir and forward views aregenerated by separate scanners, allowinga wider swath than possible with thesingle conical scan of the original ATSRdesign.

The channel selection (1.6, 3.7, 10.8and 12 μm in the infrared and 0.55, 0.66and 0.85 μm in the visible) include theEnvisat/AATSR and ERS/ATSR-2channels for continuity. Additionalchannels at 1.378 and 2.25 μm improvecloud detection, besides being used fornew products.

The instrument includes onboardradiometric sources for accurate andstable in-flight calibration. The infrareddetectors are cooled to 80K by activecoolers.

Topography packageThe topography payload consists of theSynthetic Aperture Radar Altimeter(SRAL), MWR and POD (a satnavreceiver supplemented by a laser retro-reflector). They will determine veryaccurately the height of the Earthsurface, and in particular the sea surface,relative to a precise reference frame.

loop tracking, which has problems intracking the rapid topographic changesat coastal margins and in mountainousregions.

The 26 kg MWR measures thethermal radiation emitted by Earth. Thereceived signal is proportional to theabundance of the atmospheric compo-nent emitting at the observed frequencyand the sea-surface reflectivity. Thisinformation reveals the delay added tothe altimeter pulses by moisture in thetroposphere.

Each of the three channels addresses adifferent geophysical parameter. The18.7 GHz channel, where the tropo-sphere is transparent, is influencedmainly by sea-surface reflectivity. Thisallows separation of the atmosphericsignal from the sea-surface contribu-tion in the other two channels. The23.8 GHz channel is used mainly todetermine the delay of the altimeterpulse by tropospheric water vapour. The36.5 GHz channel primarily addressesthe delay from non-precipitating clouds.The observed signals are calibrated bycomparison with a precisely known andvery stable electronic reference source.

The POD equipment provides thesatellite altitude to an accuracy of 2 cm.The 11 kg satnav receiver will operatewith Global Positioning System satell-ites for the Sentinel-3 first generation

and add Galileo for the followinggenerations. The receiver can track up to12 satellites at the same time.

The signals transmitted by the naviga-tion satellites are also disturbed by theionosphere. The effect is corrected bycomparing two signals at differentfrequencies within 1160–1590 MHz.

The receiver produces an onboardheight to within about 3 m, which isused to control SRAL’s open-looptracking and for Sentinel navigation.Ground processing yields the altitude toan accuracy of better than 8 cm within3 hours for operational applications and2 cm after some days of refinement.

Laser tracking stations will use the1 kg retro-reflector to measure thedistance to Sentinel-3 to within 2 cm.This will be done during thecommissioning phase and regularlyduring the mission to check the otherPOD results.

ConclusionGMES Sentinel-3 is a series ofoperational satellites that will guaranteeaccess to an uninterrupted flow of robustglobal data products. Together with theother Sentinels, this mission will fulfil themonitoring needs of the GMES marineand land services and climate researchcommunities for years to come. e

The radar altimeter determines thedistance to the surface by bouncingmicrowave pulses off the surface. Thetime taken is derived very precisely byground processing of the data. However,the propagation speed through theatmosphere is variable. The ionosphereand the troposphere add delaysdependent on the density of electrons inthe ionosphere, and the density of gasesand the moisture content in thetroposphere. The MWR determines theamount of water contained in the pathof the radar pulses. The altimetertransmits pulses alternatively at twofrequencies. Comparing their relativedelay, the frequency-dependent partintroduced by the ionosphere can thenbe found. The influence of gas density inthe troposphere is less variable and canbe determined sufficiently accuratelyusing meteorological data and models.

Sentinel’s own height will be measuredwith cm-accuracy by the geodetic-qualitysatnav receiver and laser retro-reflector.

The 60 kg SRAL is a dual-frequency,nadir-looking microwave radar employ-ing technologies from the CryoSat andJason altimeter missions. The mainrange measurements are performed at13.575 GHz Ku-band, while a secondfrequency at 5.41 GHz C-band allowscompensation for ionospheric effects.

A conventional pulse-limited, low-resolution mode employs autonomousclosed-loop echo tracking, and is theprimary operational mode for observinglevel homogeneous and smoothsurfaces, like open oceans or central ice-sheet plateaux.

For more variable surfaces, SRAL hastwo extra features that can be usedindependently or in combination: theSAR mode, similar to that of theCryoSat SIRAL instrument, and theopen-loop tracking mode. In the SARmode, the horizontal resolution isincreased along the ground track bysending out signals some 10 times moreoften. This will be used mainly over sea-ice and ice-sheet edges and inland water.Open-loop tracking will be used mainlyover discontinuous surfaces (like land-sea transitions) or rapidly varying

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 2928

Sentinel-3

OLCI contains five cameras to continue the work of Envisat’sMERIS

SLSTR has a wide nadir view and a narrow oblique view

oblique vieoblique vie ww

nadir vienadir vie ww

radiaradia tt oror

baseplabasepla tt ee

EarEar th th aperaper turtur e e holehole

blackbodyblackbody

The measurement principle of the topography payload Locations of the SRAL and MWR elements (green) on the satellite. SRAL is in the lower part and MWR in theupper part

Radio Frequency Unit

Digital

Processing UnitAntenna Assembly

Aguirre 8/1/07 5:01 PM Page 28

and forecast products and predictionsfrom ocean and atmosphere adding datafrom other missions and in situobservations, are the key productsdelivered to users. They provide a robust basis for downstream value-addedproducts and specialised user services.

Satellite Configuration Though carrying five instruments,Sentinel-3 is of moderate size – about1.3 t, 3.9 m high and compatible withsmall launchers like Vega (baseline) andDnepr-ST3 (back-up). It is designed fora 7-year lifetime, with 90 kg of hydrazinepropellant for 12 years of operations,including deorbiting at the end.

The layout is driven by the need toprovide a large anti-Sun side to cool theoptical instruments.

Optical instrumentsThe two optical instruments, OLCI andSLSTR, will provide a common quasi-simultaneous view of the Earth to helpdevelop synergetic products.

The 150 kg OLCI benefits fromMERIS heritage. The field-of-view isdivided between five cameras on acommon structure with the calibrationassembly. Each camera has an opticalgrating to provide the minimum baselineof 16 spectral bands required by themission together with the potential foroptional bands for improved atmo-spheric corrections.

OLCI is an autonomous instrumentwith simple interfaces to the satellite,thus allowing easy integration andminimising development risks.

topography like ice margins. In thismode, SRAL’s tracking window iscontrolled based on a priori knowledgeof the surface height, from existinghigh-resolution global digital elevationmodels, combined with knowledge ofthe location of the satellite from thesatnav receiver. The main advantage isthat the measurements are continuous,avoiding the data gaps typical of closed-

The 90 kg visible/infrared SLSTRmeasures sea- and land-surface temp-eratures, following the AATSR concept.Its rotary scan mirror mechanismproduces the wide swath of 750 km. Itfeatures ~1 km resolution at nadir forthermal-infrared channels and 500 mfor visible and shortwave infraredchannels. Like AATSR, it offers dualviews – inclined forward and near-vertical nadir – to provide robustatmospheric correction over the swath.The nadir and forward views aregenerated by separate scanners, allowinga wider swath than possible with thesingle conical scan of the original ATSRdesign.

The channel selection (1.6, 3.7, 10.8and 12 μm in the infrared and 0.55, 0.66and 0.85 μm in the visible) include theEnvisat/AATSR and ERS/ATSR-2channels for continuity. Additionalchannels at 1.378 and 2.25 μm improvecloud detection, besides being used fornew products.

The instrument includes onboardradiometric sources for accurate andstable in-flight calibration. The infrareddetectors are cooled to 80K by activecoolers.

Topography packageThe topography payload consists of theSynthetic Aperture Radar Altimeter(SRAL), MWR and POD (a satnavreceiver supplemented by a laser retro-reflector). They will determine veryaccurately the height of the Earthsurface, and in particular the sea surface,relative to a precise reference frame.

loop tracking, which has problems intracking the rapid topographic changesat coastal margins and in mountainousregions.

The 26 kg MWR measures thethermal radiation emitted by Earth. Thereceived signal is proportional to theabundance of the atmospheric compo-nent emitting at the observed frequencyand the sea-surface reflectivity. Thisinformation reveals the delay added tothe altimeter pulses by moisture in thetroposphere.

Each of the three channels addresses adifferent geophysical parameter. The18.7 GHz channel, where the tropo-sphere is transparent, is influencedmainly by sea-surface reflectivity. Thisallows separation of the atmosphericsignal from the sea-surface contribu-tion in the other two channels. The23.8 GHz channel is used mainly todetermine the delay of the altimeterpulse by tropospheric water vapour. The36.5 GHz channel primarily addressesthe delay from non-precipitating clouds.The observed signals are calibrated bycomparison with a precisely known andvery stable electronic reference source.

The POD equipment provides thesatellite altitude to an accuracy of 2 cm.The 11 kg satnav receiver will operatewith Global Positioning System satell-ites for the Sentinel-3 first generation

and add Galileo for the followinggenerations. The receiver can track up to12 satellites at the same time.

The signals transmitted by the naviga-tion satellites are also disturbed by theionosphere. The effect is corrected bycomparing two signals at differentfrequencies within 1160–1590 MHz.

The receiver produces an onboardheight to within about 3 m, which isused to control SRAL’s open-looptracking and for Sentinel navigation.Ground processing yields the altitude toan accuracy of better than 8 cm within3 hours for operational applications and2 cm after some days of refinement.

Laser tracking stations will use the1 kg retro-reflector to measure thedistance to Sentinel-3 to within 2 cm.This will be done during thecommissioning phase and regularlyduring the mission to check the otherPOD results.

ConclusionGMES Sentinel-3 is a series ofoperational satellites that will guaranteeaccess to an uninterrupted flow of robustglobal data products. Together with theother Sentinels, this mission will fulfil themonitoring needs of the GMES marineand land services and climate researchcommunities for years to come. e

The radar altimeter determines thedistance to the surface by bouncingmicrowave pulses off the surface. Thetime taken is derived very precisely byground processing of the data. However,the propagation speed through theatmosphere is variable. The ionosphereand the troposphere add delaysdependent on the density of electrons inthe ionosphere, and the density of gasesand the moisture content in thetroposphere. The MWR determines theamount of water contained in the pathof the radar pulses. The altimetertransmits pulses alternatively at twofrequencies. Comparing their relativedelay, the frequency-dependent partintroduced by the ionosphere can thenbe found. The influence of gas density inthe troposphere is less variable and canbe determined sufficiently accuratelyusing meteorological data and models.

Sentinel’s own height will be measuredwith cm-accuracy by the geodetic-qualitysatnav receiver and laser retro-reflector.

The 60 kg SRAL is a dual-frequency,nadir-looking microwave radar employ-ing technologies from the CryoSat andJason altimeter missions. The mainrange measurements are performed at13.575 GHz Ku-band, while a secondfrequency at 5.41 GHz C-band allowscompensation for ionospheric effects.

A conventional pulse-limited, low-resolution mode employs autonomousclosed-loop echo tracking, and is theprimary operational mode for observinglevel homogeneous and smoothsurfaces, like open oceans or central ice-sheet plateaux.

For more variable surfaces, SRAL hastwo extra features that can be usedindependently or in combination: theSAR mode, similar to that of theCryoSat SIRAL instrument, and theopen-loop tracking mode. In the SARmode, the horizontal resolution isincreased along the ground track bysending out signals some 10 times moreoften. This will be used mainly over sea-ice and ice-sheet edges and inland water.Open-loop tracking will be used mainlyover discontinuous surfaces (like land-sea transitions) or rapidly varying

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 2928

Sentinel-3

OLCI contains five cameras to continue the work of Envisat’sMERIS

SLSTR has a wide nadir view and a narrow oblique view

oblique vieoblique vie ww

nadir vienadir vie ww

radiaradia tt oror

baseplabasepla tt ee

EarEar th th aperaper turtur e e holehole

blackbodyblackbody

The measurement principle of the topography payload Locations of the SRAL and MWR elements (green) on the satellite. SRAL is in the lower part and MWR in theupper part

Radio Frequency Unit

Digital

Processing UnitAntenna Assembly

Aguirre 8/1/07 5:01 PM Page 28

Earth Explorers

ESA’s family of Earth Explorer satellites is

ldesigned in response to specific criticalissues raised by Earth-scientists, while

demonstrating new observation technologies.The first six Explorer missions are beingprepared for launch and, in March 2005, theAgency released a new Call-for-Ideas focusedon processes that are fundamental forunderstanding the changing ‘Earth System’. Sixcandidates were selected in May 2006 forassessment. The final selection is expected in2010, for launch in 2014/2015.

IntroductionThe Earth Explorer missions, as part ofESA’s Living Planet Programme, seek toadvance our understanding of the diff-erent ‘Earth System’ processes and todemonstrate new observing techniques.There are six missions already underdevelopment:

GOCE (Gravity Field and Steady-StateOcean Circulation Explorer), due forlaunch in early 2008, will providehigh-resolution gravity data to improvethe global and regional models ofEarth’s gravity and ‘geoid’ (the shape

Paolo Bensi, Michael Berger,Malcolm Davidson, Paul Ingmann,Joerg Langen, Helge Rebhan& Pierluigi SilvestrinScience, Application & Future TechnologiesDepartment, Directorate of Earth ObservationProgrammes, ESTEC, Noordwijk,The Netherlands

Jean-Loup Bézy, Yannig Durand, Chung-Chi Lin& Florence HélièreProjects Department, Directorate of EarthObservation Programmes, ESTEC, Noordwijk,The Netherlands

esa bulletin 131 - august 2007 31

Bensi 8/1/07 5:03 PM Page 30

Earth Explorers

ESA’s family of Earth Explorer satellites is

ldesigned in response to specific criticalissues raised by Earth-scientists, while

demonstrating new observation technologies.The first six Explorer missions are beingprepared for launch and, in March 2005, theAgency released a new Call-for-Ideas focusedon processes that are fundamental forunderstanding the changing ‘Earth System’. Sixcandidates were selected in May 2006 forassessment. The final selection is expected in2010, for launch in 2014/2015.

IntroductionThe Earth Explorer missions, as part ofESA’s Living Planet Programme, seek toadvance our understanding of the diff-erent ‘Earth System’ processes and todemonstrate new observing techniques.There are six missions already underdevelopment:

GOCE (Gravity Field and Steady-StateOcean Circulation Explorer), due forlaunch in early 2008, will providehigh-resolution gravity data to improvethe global and regional models ofEarth’s gravity and ‘geoid’ (the shape

Paolo Bensi, Michael Berger,Malcolm Davidson, Paul Ingmann,Joerg Langen, Helge Rebhan& Pierluigi SilvestrinScience, Application & Future TechnologiesDepartment, Directorate of Earth ObservationProgrammes, ESTEC, Noordwijk,The Netherlands

Jean-Loup Bézy, Yannig Durand, Chung-Chi Lin& Florence HélièreProjects Department, Directorate of EarthObservation Programmes, ESTEC, Noordwijk,The Netherlands

esa bulletin 131 - august 2007 31

Bensi 8/1/07 5:03 PM Page 30

of a global ocean at rest used as areference).

SMOS (Soil Moisture and OceanSalinity), due for launch in 2008, willglobally map soil moisture and oceansalinity to improve the representationof land in global atmosphericcirculation models and to characterisethe role of the ocean in the climatesystem.

ADM-Aeolus (Atmospheric DynamicsMission), due for launch in 2009, willmake novel advances in global wind-profile observations and provideglobal wind information that is crucialto climate research and numericalweather prediction.

CryoSat-2, due for launch in 2009, willdetermine the rate of change ofvariations in the thickness and mass ofpolar marine ice and continental ice-sheets in response to climate changes.CryoSat-2 replaces CryoSat, the firstExplorer mission, which was lost atlaunch in 2005.

Swarm, due for launch in 2010, is aconstellation of three satellites tosurvey the geomagnetic field and itsevolution. It will provide new insightsinto the Earth System by improvingour understanding of the Sun’sinfluence and Earth’s interior.

EarthCARE (Earth Clouds and Radia-tion Explorer), due for launch in 2012,is a joint European-Japanese missionto measure cloud and aerosol proper-ties to help understand their inter-actions with Earth’s radiative processesand climate-change predictions.

In March 2005, ESA released a newCall-for-Ideas to scientists from ESAMember States and Canada to solicitproposals for the next Earth Explorer.The scientific priorities focused on theglobal carbon and water cycles,atmospheric chemistry, climate and thehuman element as a cross-cutting issue.Twenty-four proposals were receivedand evaluated as ‘Core’ missions (theseaddress specific areas of great scientificinterest; ‘Opportunity’ missions arefaster, cheaper and not necessarily led byESA). Six candidates were short-listed

Analysing the reflected radar beamwould provide information on the forestvertical structure and height, with thepotential to extend the observationrange and/or to increase the estimationaccuracy of biomass products.

The secondary objectives arise fromthe opportunity to explore Earth’ssurface with a longwave SAR for thefirst time. New information on icestructure, ice thickness and subsurfacegeomorphology in arid areas would beexpected.

The satellite would carry the side-looking radar in a Sun-synchronousorbit optimised to reduce ionosphericeffects on signal propagation. The orbitwould cover all forested areas every25 days globally to satisfy the majormission objectives.

BIOMASS would be the first missiondedicated to estimating biomassglobally using low-frequency SARobservations.

TRAQChanges in the composition of Earth’stroposphere (altitude 0–7/17 km) are aserious and growing problem in manyregions of the world. The compositionaffects air quality regionally andglobally as well as the climate viaradiatively active trace gases andaerosols. TRAQ would assess the airquality changes at global and regionalscales, determine the strength and

in May 2006 for dedicated assessments,with industrial activities beginning inMay/June 2007:

– BIOMASS (to monitor Earth’s biomassfor carbon assessment);

– TRAQ (TRopospheric compositionand Air Quality);

– PREMIER (PRocess Explorationthrough Measurement of Infraredand millimeter-wave Emitted Radia-tion);

– FLEX (FLuorescence Explorer);– A-SCOPE (Advanced Space Carbon

and Climate Observation of PlanetEarth);

– CoReH2O (Cold Regions HydrologyHigh-resolution Observatory).

BIOMASSThe greatest uncertainties in the globalcarbon cycle involve estimating howcarbon dioxide is taken up by land. Themission aims to improve the presentassessment and future projection of theterrestrial carbon cycle by providingconsistent global maps of forest biomassand forest area, forest disturbances andrecovery with time, and the extent andevolution of forest flooding. Forestbiomass is a key factor in the carboncycle but it falls in a critical gap inexisting measurement techniques. Whencoupled with biophysical models, above-ground biomass provides information oncarbon dioxide stocks and fluxes and is a

distribution of the sources and sinks oftrace gases and aerosols influencing airquality, and help in the understandingof the role of tropospheric compositionin the global change.

A new synergistic sensor concept isproposed: a high spectral resolutionpushbroom shortwave spectrometer(SWS) in the range from ultraviolet tonear-infrared; a high spectral resolutionacross-track scanning longwave spectro-meter (LWS) in the thermal-infraredwith an embedded cloud imager and a multi-view polarisation-resolvingpushbroom radiometer. A shortwave-infrared band is also required; it would be included either in the LWS orSWS.

The cloud imager is a dual-bandinfrared instrument that would optimisein real time the pointing direction of thethermal-infrared spectrometer towardsareas clear of clouds. The mission willoffer a pixel size of 15–40 km,depending on the spectral bands.

TRAQ’s orbit is selected to offer near-global coverage and unique diurnal timesampling with up to five daytimeobservations over Europe and othermid-latitude regions. This can beachieved by using a non-Sun-synchronous low drifting orbit with aninclination around 57º.

TRAQ would provide the followingparameters: ozone, nitrogen dioxide,sulphur dioxide, HCHO (formalde-hyde), water vapour and HCOOCH(1,2-ethanedione) tropospheric columnsfrom the ultraviolet/visible/near-infraredspectral region; carbon monoxide andmethane tropospheric columns from theshortwave infrared spectral region;height-resolved tropospheric profiles ofozone and carbon monoxide from thethermal-infrared channels; detailedtropospheric aerosol characterisationfrom the multi-view polarisation-resolving radiometer and in combina-tion with the ultraviolet/visible/near-infrared spectrometer.

TRAQ would be the first mission fullydedicated to air quality and the scienceissues around tropospheric compositionand global change.

PREMIERThe primary aim of PREMIER is toexplore the processes that control thecomposition of the mid/upper tropo-sphere and lower stratosphere (altitude3/10–51/58 km). It would be the firstmission to explore from space the linksbetween atmospheric composition andclimate globally in unprecedented detailand, for the first time, with sufficientresolution.

PREMIER would observe the distri-butions of trace gases, particulates andtemperature in this region down to finerscales than any previous satellite mission.It would also facilitate integration withmeasurements made at higher resolutionat particular locations and times byground and airborne instruments.

The secondary aim is to the exploreprocesses that control the compositionof the lower troposphere/boundarylayer and the links to higher layers.

Through synergy with Europe’s

sensitive indicator of changes in land useand natural biophysical processes.

The BIOMASS primary objectiveswould be achieved through a P-band(435 MHz) synthetic aperture radar(SAR). Finding the above-groundbiomass from calibrated SAR imageswill take advantage of the high sensitiv-ity of P-band reflection to biomass.

Complementary classification techni-ques would exploit the polarisation ofthe radar signatures from different typesof forest to label surface features bycomparison with known reference cases.

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 3332

Earth Explorers

TRAQ Characteristics

Mission duration: 3–5 yearsOrbit: drifting low orbit, inclination ~57º Coverage: latitudes 40ºS–60ºNRevisit time: 3 monthsTemporal sampling: up to 5 times/day over

continental areas within 40–55ºNInstruments: UV/visible/near-infrared

spectrometer (SWS); thermal-infraredspectrometer (LWS); shortwave infrared(either SWS or LWS); infrared CloudImager; multi-view polarisation resolvingradiometer

Resolution: 15–40 km (UV/shortwaveinfrared), 15 km (thermal-infrared); 1 km(Cloud Imager); 1–4 km (multi-viewpolarisation resolving radiometer)

BIOMASS Characteristics

Mission duration: 5 yearsOrbit: Sun-synchronous, local time ~06:00 Coverage: global, vegetated areasRevisit time: 25 daysInstrument: P-band (435 MHz) synthetic

aperture radarPolarisation: full polarimetry and/or

circular/dual polarisationData acquisition: single-pass/repeat-pass

polarimetric interferometryResolution: ≤50 x 50 m (≥4 looks)Swath width: ≥100 km

BIOMASS: global measurements of forest biomassTRAQ: air quality and long-range transportof air pollution

Bensi 8/1/07 5:04 PM Page 32

of a global ocean at rest used as areference).

SMOS (Soil Moisture and OceanSalinity), due for launch in 2008, willglobally map soil moisture and oceansalinity to improve the representationof land in global atmosphericcirculation models and to characterisethe role of the ocean in the climatesystem.

ADM-Aeolus (Atmospheric DynamicsMission), due for launch in 2009, willmake novel advances in global wind-profile observations and provideglobal wind information that is crucialto climate research and numericalweather prediction.

CryoSat-2, due for launch in 2009, willdetermine the rate of change ofvariations in the thickness and mass ofpolar marine ice and continental ice-sheets in response to climate changes.CryoSat-2 replaces CryoSat, the firstExplorer mission, which was lost atlaunch in 2005.

Swarm, due for launch in 2010, is aconstellation of three satellites tosurvey the geomagnetic field and itsevolution. It will provide new insightsinto the Earth System by improvingour understanding of the Sun’sinfluence and Earth’s interior.

EarthCARE (Earth Clouds and Radia-tion Explorer), due for launch in 2012,is a joint European-Japanese missionto measure cloud and aerosol proper-ties to help understand their inter-actions with Earth’s radiative processesand climate-change predictions.

In March 2005, ESA released a newCall-for-Ideas to scientists from ESAMember States and Canada to solicitproposals for the next Earth Explorer.The scientific priorities focused on theglobal carbon and water cycles,atmospheric chemistry, climate and thehuman element as a cross-cutting issue.Twenty-four proposals were receivedand evaluated as ‘Core’ missions (theseaddress specific areas of great scientificinterest; ‘Opportunity’ missions arefaster, cheaper and not necessarily led byESA). Six candidates were short-listed

Analysing the reflected radar beamwould provide information on the forestvertical structure and height, with thepotential to extend the observationrange and/or to increase the estimationaccuracy of biomass products.

The secondary objectives arise fromthe opportunity to explore Earth’ssurface with a longwave SAR for thefirst time. New information on icestructure, ice thickness and subsurfacegeomorphology in arid areas would beexpected.

The satellite would carry the side-looking radar in a Sun-synchronousorbit optimised to reduce ionosphericeffects on signal propagation. The orbitwould cover all forested areas every25 days globally to satisfy the majormission objectives.

BIOMASS would be the first missiondedicated to estimating biomassglobally using low-frequency SARobservations.

TRAQChanges in the composition of Earth’stroposphere (altitude 0–7/17 km) are aserious and growing problem in manyregions of the world. The compositionaffects air quality regionally andglobally as well as the climate viaradiatively active trace gases andaerosols. TRAQ would assess the airquality changes at global and regionalscales, determine the strength and

in May 2006 for dedicated assessments,with industrial activities beginning inMay/June 2007:

– BIOMASS (to monitor Earth’s biomassfor carbon assessment);

– TRAQ (TRopospheric compositionand Air Quality);

– PREMIER (PRocess Explorationthrough Measurement of Infraredand millimeter-wave Emitted Radia-tion);

– FLEX (FLuorescence Explorer);– A-SCOPE (Advanced Space Carbon

and Climate Observation of PlanetEarth);

– CoReH2O (Cold Regions HydrologyHigh-resolution Observatory).

BIOMASSThe greatest uncertainties in the globalcarbon cycle involve estimating howcarbon dioxide is taken up by land. Themission aims to improve the presentassessment and future projection of theterrestrial carbon cycle by providingconsistent global maps of forest biomassand forest area, forest disturbances andrecovery with time, and the extent andevolution of forest flooding. Forestbiomass is a key factor in the carboncycle but it falls in a critical gap inexisting measurement techniques. Whencoupled with biophysical models, above-ground biomass provides information oncarbon dioxide stocks and fluxes and is a

distribution of the sources and sinks oftrace gases and aerosols influencing airquality, and help in the understandingof the role of tropospheric compositionin the global change.

A new synergistic sensor concept isproposed: a high spectral resolutionpushbroom shortwave spectrometer(SWS) in the range from ultraviolet tonear-infrared; a high spectral resolutionacross-track scanning longwave spectro-meter (LWS) in the thermal-infraredwith an embedded cloud imager and a multi-view polarisation-resolvingpushbroom radiometer. A shortwave-infrared band is also required; it would be included either in the LWS orSWS.

The cloud imager is a dual-bandinfrared instrument that would optimisein real time the pointing direction of thethermal-infrared spectrometer towardsareas clear of clouds. The mission willoffer a pixel size of 15–40 km,depending on the spectral bands.

TRAQ’s orbit is selected to offer near-global coverage and unique diurnal timesampling with up to five daytimeobservations over Europe and othermid-latitude regions. This can beachieved by using a non-Sun-synchronous low drifting orbit with aninclination around 57º.

TRAQ would provide the followingparameters: ozone, nitrogen dioxide,sulphur dioxide, HCHO (formalde-hyde), water vapour and HCOOCH(1,2-ethanedione) tropospheric columnsfrom the ultraviolet/visible/near-infraredspectral region; carbon monoxide andmethane tropospheric columns from theshortwave infrared spectral region;height-resolved tropospheric profiles ofozone and carbon monoxide from thethermal-infrared channels; detailedtropospheric aerosol characterisationfrom the multi-view polarisation-resolving radiometer and in combina-tion with the ultraviolet/visible/near-infrared spectrometer.

TRAQ would be the first mission fullydedicated to air quality and the scienceissues around tropospheric compositionand global change.

PREMIERThe primary aim of PREMIER is toexplore the processes that control thecomposition of the mid/upper tropo-sphere and lower stratosphere (altitude3/10–51/58 km). It would be the firstmission to explore from space the linksbetween atmospheric composition andclimate globally in unprecedented detailand, for the first time, with sufficientresolution.

PREMIER would observe the distri-butions of trace gases, particulates andtemperature in this region down to finerscales than any previous satellite mission.It would also facilitate integration withmeasurements made at higher resolutionat particular locations and times byground and airborne instruments.

The secondary aim is to the exploreprocesses that control the compositionof the lower troposphere/boundarylayer and the links to higher layers.

Through synergy with Europe’s

sensitive indicator of changes in land useand natural biophysical processes.

The BIOMASS primary objectiveswould be achieved through a P-band(435 MHz) synthetic aperture radar(SAR). Finding the above-groundbiomass from calibrated SAR imageswill take advantage of the high sensitiv-ity of P-band reflection to biomass.

Complementary classification techni-ques would exploit the polarisation ofthe radar signatures from different typesof forest to label surface features bycomparison with known reference cases.

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 3332

Earth Explorers

TRAQ Characteristics

Mission duration: 3–5 yearsOrbit: drifting low orbit, inclination ~57º Coverage: latitudes 40ºS–60ºNRevisit time: 3 monthsTemporal sampling: up to 5 times/day over

continental areas within 40–55ºNInstruments: UV/visible/near-infrared

spectrometer (SWS); thermal-infraredspectrometer (LWS); shortwave infrared(either SWS or LWS); infrared CloudImager; multi-view polarisation resolvingradiometer

Resolution: 15–40 km (UV/shortwaveinfrared), 15 km (thermal-infrared); 1 km(Cloud Imager); 1–4 km (multi-viewpolarisation resolving radiometer)

BIOMASS Characteristics

Mission duration: 5 yearsOrbit: Sun-synchronous, local time ~06:00 Coverage: global, vegetated areasRevisit time: 25 daysInstrument: P-band (435 MHz) synthetic

aperture radarPolarisation: full polarimetry and/or

circular/dual polarisationData acquisition: single-pass/repeat-pass

polarimetric interferometryResolution: ≤50 x 50 m (≥4 looks)Swath width: ≥100 km

BIOMASS: global measurements of forest biomassTRAQ: air quality and long-range transportof air pollution

Bensi 8/1/07 5:04 PM Page 32

MetOp satellite, flying in tandem, thecomposition of the lower tropospherewill be clearly discriminated from that ofhigher layers. The mission objectives callfor 3-D sounding of the mid/uppertroposphere and stratosphere by two

instruments are: a coarse resolutionvisible/near-infrared spectrometer and a6-channel shortwave infrared imager forbasic vegetation parameters, a thermal-infrared radiometer with four channelsfor estimating the temperature of thevegetation canopy. An optional off-nadir two–three band visible/ short-wave-infrared imager would help tocorrect for atmospheric effects.

A single satellite in a Sun-synchronousorbit is the baseline for the mission. Alocal time of 10:00 would provideadequate balance between maximumfluorescence emission and maximumsolar illumination. A spatial resolutionof the order 100–300 m is required.

A-SCOPEA-SCOPE, like other missions toobserve carbon dioxide from space,would be an innovative source of datafor understanding the carbon cycle andvalidating inventories of greenhouse gasemissions. It would provide near-globalcoverage with good time resolution,mapping the sources and sinks ofcarbon dioxide on a scale of 500 km orbetter. This is a major improvement overtoday’s observation network and forth-coming in situ and space systems.

A-SCOPE would be the first missiondedicated to measuring carbon dioxidewith an active ‘Differential AbsorptionLidar’ (DIAL) sensor. It would providebetter accuracy and spatial andtemporal coverage than the plannedsatellites carrying passive sensors: OCO(Orbiting Carbon Observatory; NASA)

complementary limb-sounders at infra-red and mm/sub-mm wavelengths. Thelimb would be imaged at high resolutionto account for the effects of clouds andto derive cloud/aerosol properties.

The infrared sounder is an imagingFourier transform spectrometer either ina high spectral resolution mode, opti-mised for observation of minor tracegases or in a high spatial resolutionmode, optimised to resolve atmosphericstructure.

The mm/sub-mm sounder is a limb-sounding heterodyne receiver with achannel in the 320–360 GHz range formeasurements of the main target speciesof water, ozone and carbon monoxide(or with a slight spectral shift to observehydrogen cyanide, HDO water isotope,nitrous oxide, chlorine monoxide, nitricacid) in the upper troposphere/lowerstratosphere altitude range, and achannel in the 488–504 GHz range withimproved sensitivity to stratospherictarget species (such as chlorine mon-oxide, nitrous oxide, water and itsisotopes). The instrument would bedeveloped as a Swedish national contri-bution to the mission.

FLEXThe mission would improve our know-ledge of the carbon cycle by globallymeasuring the efficiency of photo-synthesis of ecosystems. Photosynthesisby land vegetation is an important

and GOSAT (Greenhouse gases Observ-ing Satellite; JAXA). Only active sensingwould provide high-accuracy measure-ments and truly global, day/nightcoverage under both clear and broken-cloud conditions.

DIAL would measure the reflectionsfrom Earth’s surface and clouds tops oflaser pulses at slightly different wave-lengths. Carbon dioxide in the atmos-phere would absorb some of the laserlight, varying with wavelength. Thedifferences between the two wavelengthsyields the concentration of carbon

dioxide, with a target minimum accuracyof 1.5 parts per million by volume and agoal of 0.5 ppmv. Suitable absorptioncan be found in the near-infrared around1.6 μm and 2.1 μm.

In both spectral regions, temperaturesensitivity and interference from watervapour and other trace gases can beminimised by careful selection of thelaser’s exact wavelengths.

A camera operating in the visible,near-infrared and thermal-infrared witha narrow swath width of 50 km wouldput the measurements in context with abroader view of the clouds and Earth’ssurface texture.

CoReH2OThe mission aims at all four sciencepriorities identified in the Call for Ideas,with emphasis on the global water cycleand significant contributions inunderstanding the global carbon cycle,atmospheric chemistry and climate, aswell as assessing the human impact onthese aspects.

The mission would focus on detailedobservations of important snow, ice andwater-cycle parameters. It would improveour understanding and modelling ofsurface processes and surface/atmos-phere exchange mechanisms in regionswhere snow and ice play a major role inthe water and energy cycles, as well as inbiospheric processes.

The key parameters to be founddescribe a snow layer: extent, thicknessand water-equivalent (the amount ofwater from the instantaneous melting of

component of the global carbon cycle,closely linked to the hydrological cyclethrough transpiration. This type ofinformation has never been availablebefore from space observations.

Fluorescence under sunlight is asensitive and direct probe of photo-synthesis in both healthy and perturbedvegetation. It gives an early indication ofplant stress before it can be observed bymore conventional means. For FLEX,direct fluorescence measurements ofvegetation chlorophyll are proposed,complemented by hyperspectral reflect-ance and canopy temperature to helpinterpret the fluorescence.

The core instrument is a spectrometerto measure the fluorescence in the blue,red and far-red using the ‘FraunhoferLine Discriminator’ method.

The fluorescence of chlorophyll in thered and far-red is the key for monitoringphotosynthesis. Blue-green fluorescenceadds information about the vegetation’sstatus and health. The complementary

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 3534

Earth Explorers

FLEX Characteristics

Mission duration: 3–5 seasonal cycles innorthern and southern hemispheres

Orbit: Sun-synchronous, local timedescending node around 10:00

Coverage: global coverage of land surfaces(56ºS–75ºN)

Revisit time: 1 weekInstruments: Fluorescence Spectrometer;

Visible/Near-Infrared ImagingSpectrometer (0.45–1 μm); ShortwaveInfrared Imager (1.4–2.2 μm); ThermalInfrared Imaging Radiometer (8.8–12 μm);optional multi-view Visible/ShortwaveInfrared Imager

Resolution: 100–300 m

A-SCOPE Characteristics

Mission duration: 3–5 yearsOrbit: Sun-synchronous Coverage: near-globalInstruments: nadir-viewing pulsed-laser DIAL

at 2.1 μm or 1.6 μm; visible/near-infrared/thermal-infrared Imaging Camera

Vertical resolution: total columnHorizontal resolution: DIAL 50 km along-

track; Imaging Camera 100 m

PREMIER Characteristics

Mission duration: 4 yearsOrbit: Sun-synchronous in tandem with

MetOp (835 km)Coverage: near-global, latitudes 80ºS–80ºNInstruments: Infrared Limb Sounder (IRLS);

Infrared Cloud Imager (IRCI); MicrowaveLimb Sounder (MWLS)

Vertical coverage: IRLS 48 km (3/10–51/58km arctic/tropics); IRCI 25 km(3/10–28/35 km arctic/tropics); MWLS23 km (5–28 km upper troposphere/lowerstratosphere, 12–35 km stratosphericmode)

Vertical sampling: IRLS 0.5–2 km (dependingon mode and range); IRCI 0.5 km; MWLS1.5 km

Horizontal sampling: IRLS 25–80 km across-track, 50–100 km along-track; IRCI 4 kmacross-track, 8–50 km along-track; MWLS≤ 50 km (≤ 300 km in stratospheric mode)along-track

PREMIER: atmospheric processes linking trace gases,radiation, chemistry and climate

FLEX: global photosynthesis A-SCOPE: global carboncycle and regional carbondioxide fluxes

Bensi 8/1/07 5:04 PM Page 34

MetOp satellite, flying in tandem, thecomposition of the lower tropospherewill be clearly discriminated from that ofhigher layers. The mission objectives callfor 3-D sounding of the mid/uppertroposphere and stratosphere by two

instruments are: a coarse resolutionvisible/near-infrared spectrometer and a6-channel shortwave infrared imager forbasic vegetation parameters, a thermal-infrared radiometer with four channelsfor estimating the temperature of thevegetation canopy. An optional off-nadir two–three band visible/ short-wave-infrared imager would help tocorrect for atmospheric effects.

A single satellite in a Sun-synchronousorbit is the baseline for the mission. Alocal time of 10:00 would provideadequate balance between maximumfluorescence emission and maximumsolar illumination. A spatial resolutionof the order 100–300 m is required.

A-SCOPEA-SCOPE, like other missions toobserve carbon dioxide from space,would be an innovative source of datafor understanding the carbon cycle andvalidating inventories of greenhouse gasemissions. It would provide near-globalcoverage with good time resolution,mapping the sources and sinks ofcarbon dioxide on a scale of 500 km orbetter. This is a major improvement overtoday’s observation network and forth-coming in situ and space systems.

A-SCOPE would be the first missiondedicated to measuring carbon dioxidewith an active ‘Differential AbsorptionLidar’ (DIAL) sensor. It would providebetter accuracy and spatial andtemporal coverage than the plannedsatellites carrying passive sensors: OCO(Orbiting Carbon Observatory; NASA)

complementary limb-sounders at infra-red and mm/sub-mm wavelengths. Thelimb would be imaged at high resolutionto account for the effects of clouds andto derive cloud/aerosol properties.

The infrared sounder is an imagingFourier transform spectrometer either ina high spectral resolution mode, opti-mised for observation of minor tracegases or in a high spatial resolutionmode, optimised to resolve atmosphericstructure.

The mm/sub-mm sounder is a limb-sounding heterodyne receiver with achannel in the 320–360 GHz range formeasurements of the main target speciesof water, ozone and carbon monoxide(or with a slight spectral shift to observehydrogen cyanide, HDO water isotope,nitrous oxide, chlorine monoxide, nitricacid) in the upper troposphere/lowerstratosphere altitude range, and achannel in the 488–504 GHz range withimproved sensitivity to stratospherictarget species (such as chlorine mon-oxide, nitrous oxide, water and itsisotopes). The instrument would bedeveloped as a Swedish national contri-bution to the mission.

FLEXThe mission would improve our know-ledge of the carbon cycle by globallymeasuring the efficiency of photo-synthesis of ecosystems. Photosynthesisby land vegetation is an important

and GOSAT (Greenhouse gases Observ-ing Satellite; JAXA). Only active sensingwould provide high-accuracy measure-ments and truly global, day/nightcoverage under both clear and broken-cloud conditions.

DIAL would measure the reflectionsfrom Earth’s surface and clouds tops oflaser pulses at slightly different wave-lengths. Carbon dioxide in the atmos-phere would absorb some of the laserlight, varying with wavelength. Thedifferences between the two wavelengthsyields the concentration of carbon

dioxide, with a target minimum accuracyof 1.5 parts per million by volume and agoal of 0.5 ppmv. Suitable absorptioncan be found in the near-infrared around1.6 μm and 2.1 μm.

In both spectral regions, temperaturesensitivity and interference from watervapour and other trace gases can beminimised by careful selection of thelaser’s exact wavelengths.

A camera operating in the visible,near-infrared and thermal-infrared witha narrow swath width of 50 km wouldput the measurements in context with abroader view of the clouds and Earth’ssurface texture.

CoReH2OThe mission aims at all four sciencepriorities identified in the Call for Ideas,with emphasis on the global water cycleand significant contributions inunderstanding the global carbon cycle,atmospheric chemistry and climate, aswell as assessing the human impact onthese aspects.

The mission would focus on detailedobservations of important snow, ice andwater-cycle parameters. It would improveour understanding and modelling ofsurface processes and surface/atmos-phere exchange mechanisms in regionswhere snow and ice play a major role inthe water and energy cycles, as well as inbiospheric processes.

The key parameters to be founddescribe a snow layer: extent, thicknessand water-equivalent (the amount ofwater from the instantaneous melting of

component of the global carbon cycle,closely linked to the hydrological cyclethrough transpiration. This type ofinformation has never been availablebefore from space observations.

Fluorescence under sunlight is asensitive and direct probe of photo-synthesis in both healthy and perturbedvegetation. It gives an early indication ofplant stress before it can be observed bymore conventional means. For FLEX,direct fluorescence measurements ofvegetation chlorophyll are proposed,complemented by hyperspectral reflect-ance and canopy temperature to helpinterpret the fluorescence.

The core instrument is a spectrometerto measure the fluorescence in the blue,red and far-red using the ‘FraunhoferLine Discriminator’ method.

The fluorescence of chlorophyll in thered and far-red is the key for monitoringphotosynthesis. Blue-green fluorescenceadds information about the vegetation’sstatus and health. The complementary

Earth Observation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 3534

Earth Explorers

FLEX Characteristics

Mission duration: 3–5 seasonal cycles innorthern and southern hemispheres

Orbit: Sun-synchronous, local timedescending node around 10:00

Coverage: global coverage of land surfaces(56ºS–75ºN)

Revisit time: 1 weekInstruments: Fluorescence Spectrometer;

Visible/Near-Infrared ImagingSpectrometer (0.45–1 μm); ShortwaveInfrared Imager (1.4–2.2 μm); ThermalInfrared Imaging Radiometer (8.8–12 μm);optional multi-view Visible/ShortwaveInfrared Imager

Resolution: 100–300 m

A-SCOPE Characteristics

Mission duration: 3–5 yearsOrbit: Sun-synchronous Coverage: near-globalInstruments: nadir-viewing pulsed-laser DIAL

at 2.1 μm or 1.6 μm; visible/near-infrared/thermal-infrared Imaging Camera

Vertical resolution: total columnHorizontal resolution: DIAL 50 km along-

track; Imaging Camera 100 m

PREMIER Characteristics

Mission duration: 4 yearsOrbit: Sun-synchronous in tandem with

MetOp (835 km)Coverage: near-global, latitudes 80ºS–80ºNInstruments: Infrared Limb Sounder (IRLS);

Infrared Cloud Imager (IRCI); MicrowaveLimb Sounder (MWLS)

Vertical coverage: IRLS 48 km (3/10–51/58km arctic/tropics); IRCI 25 km(3/10–28/35 km arctic/tropics); MWLS23 km (5–28 km upper troposphere/lowerstratosphere, 12–35 km stratosphericmode)

Vertical sampling: IRLS 0.5–2 km (dependingon mode and range); IRCI 0.5 km; MWLS1.5 km

Horizontal sampling: IRLS 25–80 km across-track, 50–100 km along-track; IRCI 4 kmacross-track, 8–50 km along-track; MWLS≤ 50 km (≤ 300 km in stratospheric mode)along-track

PREMIER: atmospheric processes linking trace gases,radiation, chemistry and climate

FLEX: global photosynthesis A-SCOPE: global carboncycle and regional carbondioxide fluxes

Bensi 8/1/07 5:04 PM Page 34

a snow pack). These observations willhelp data-assimilation systems, numericalweather prediction and climate models,and the understanding and modelling ofland-cryosphere-atmosphere exchangeprocesses.

The secondary objectives aim at ice-surface parameters that would help theanalyses of sea-ice dynamics in local andglobal climate models.

Producing this geophysical informa-tion depends on backscatter measure-ments from a synthetic aperture radar atX- and Ku-band at relatively highresolution. Ku-band is more sensitive toshallow dry snow, while X-band providesgreater penetration of deeper snowlayers. The combination of observationsat two frequencies would improve theaccuracy of the snow information andprovide a high level of information onsea ice, ice sheets and glaciers.

Measurements of the polarisation ofthe reflected radar pulses are importantfor separating surface and volumescattering and for estimating the snowwater equivalent.

The mission is based on a singlesatellite in a Sun-synchronous orbit witha local time early in the morning ataround 06:00 to avoid the effects ofdaily warming and melting. The missionwould be divided into two phases: thefirst phase (2 years) with revisits every3 days, in order to observe the morerapid processes in selected test areas.These frequent visits are at the expenseof limited coverage. The second phase(2–3 years) would revisit every 15 days,with near-global coverage of snow andice areas.

The Selection ProcessThe current cycle will lead to theselection in 2010 of the seventh EarthExplorer, due for launch in 2014/2015.As in the previous cycles, the process hasfour steps. The first step (Phase-0:mission assessment) began in 2006 withthe nomination of the Mission Assess-ment Groups that provide independentadvice to the Agency for the definitionof the detailed scientific objectives ofthe missions, the consolidation of themission requirements, the definition ofrequired scientific support and theproduction of the Reports for Assess-ment. The other major element of thisstep is the Phase-0 industrial studies,beginning in May/June 2007 to identifyend-to-end implementation concepts foreach mission as well as their preliminaryfeasibility in terms of required technol-ogy and compliance with programmeconstraints. The assessment step willconclude with a User ConsultationProcess that reviews the assessments andproposes a short-list of candidates toenter the next step in 2009 (Phase-A:mission feasibility).

At the end of Phase-A in 2010, asecond User Consultation Process willrecommend the final candidate to enterthe development phases (B/C/D) andfinally join the Earth Explorer family asthe seventh mission of the series.

AcknowledgmentsThe authors thank the members of theMission Advisory Groups supportingESA in the mission definition. e

Earth Observation

esa bulletin 131 - august 2007 www.esa.int36

CoReH2O Characteristics

Mission duration: 5 years Orbit: Sun-synchronous, local time 06:00 Coverage: test sites (phase-1); global

coverage of snow and ice areas (phase-2)Revisit time: 3 days (phase-1); ≤15 days

(phase-2)Instrument: dual-frequency (9.6/17.2 GHz)

synthetic aperture radarPolarisation: dual (vertical-vertical; vertical-

horizontal)Resolution: ≤50 x 50 m (≥5 looks)Swath width: ≥100 km

CoReH2O: detailed observations of key snow,ice and water cycle characteristics

Bensi 8/1/07 5:04 PM Page 36

SMART-1

SMART-1 was launched in September 2003

land impacted the Moon 3 years later. Itwas the first of ESA’s Small Missions for

Advanced Research in Technology, with themain goal of testing electric propulsion.Following a spectacular navigation strategy,the craft reached the Moon, where its orbit wasoptimised for scientific observations. Theinstruments provided data throughout themission, interrupted only by manoeuvres. Thelast of these had to be done with the attitudethrusters after exhausting the ion thruster’sxenon fuel. The impact was observed fromEarth by radio and infrared telescopesworldwide in an international campaign.

At the MoonImmediately after the Moon’s gravitycaptured SMART-1 on 15 November2004, the ion engine was used to beginthe spiral down into the final orbit. Theoperational lunar orbit was reached at theend of February 2005, requiring 13.5 kgof xenon and 236 thrust periodstotalling 953 hours by the ion engine.The favourable launch date and thegood performance of the electric pro-pulsion system and the solar panels

Octavio Camino & Jurriaan de BruinSolar and Planetary Missions System Division,Operations Department, Directorate ofOperations and Infrastructure, ESOC,Darmstadt, Germany

Johannes SchoenmaekersFlight Dynamics Division, EngineeringDepartment, Directorate of Operations andInfrastructure, ESOC, Darmstadt, Germany

Peter Rathsman, Joakim Kugelberg& Per BodinSwedish Space Corporation, Sweden

esa bulletin 131 - august 2007 39

Camino 8/1/07 5:08 PM Page 38

SMART-1

SMART-1 was launched in September 2003

land impacted the Moon 3 years later. Itwas the first of ESA’s Small Missions for

Advanced Research in Technology, with themain goal of testing electric propulsion.Following a spectacular navigation strategy,the craft reached the Moon, where its orbit wasoptimised for scientific observations. Theinstruments provided data throughout themission, interrupted only by manoeuvres. Thelast of these had to be done with the attitudethrusters after exhausting the ion thruster’sxenon fuel. The impact was observed fromEarth by radio and infrared telescopesworldwide in an international campaign.

At the MoonImmediately after the Moon’s gravitycaptured SMART-1 on 15 November2004, the ion engine was used to beginthe spiral down into the final orbit. Theoperational lunar orbit was reached at theend of February 2005, requiring 13.5 kgof xenon and 236 thrust periodstotalling 953 hours by the ion engine.The favourable launch date and thegood performance of the electric pro-pulsion system and the solar panels

Octavio Camino & Jurriaan de BruinSolar and Planetary Missions System Division,Operations Department, Directorate ofOperations and Infrastructure, ESOC,Darmstadt, Germany

Johannes SchoenmaekersFlight Dynamics Division, EngineeringDepartment, Directorate of Operations andInfrastructure, ESOC, Darmstadt, Germany

Peter Rathsman, Joakim Kugelberg& Per BodinSwedish Space Corporation, Sweden

esa bulletin 131 - august 2007 39

Camino 8/1/07 5:08 PM Page 38

during the cruise from Earth saved5.5 kg of xenon, which could then beused to lower the highest point of theorbit (‘apolune’) from the planned10 000 km to 4600 km, improving theresolution of the science observations.

After achieving the primary goal oftesting and validating SMART-1’s newtechnologies – especially the electricpropulsion system – the mission was

up the downstream low-pressure tank toabout 2 bars, the bare minimum thatwas needed to fire the ion engine beforeit flamed out. The last pulse lasted just10 minutes before the engine flamed outfor the last time.

Science at the MoonAll of the scientific instruments werecalled upon during the observationphase. The team at the Science andTechnology Operations Centre atESTEC developed special tools to getthe most out of these observations.Most observations were done with theinstruments pointing towards theMoon’s centre, with the solar arraysquare-on to the Sun (‘nadir pointing’).Two special pointing modes could alsobe used for short periods: push-broomand target tracking.

In the push-broom mode, AMIE tooka sequence of images along the ground-track. Colour images were created bycombining the same scenes shot throughdifferent filters.

Occasionally, SMART-1 used target-tracking: as the craft travelled aroundthe Moon at several hundred metres persecond, AMIE was kept pointing at thesame target.

Solar array off-pointingAnalysis of the expected Moon impactby the Thermal & Structures Division atESTEC concluded that the solar arraytemperature could rise too high in May2006. For some time during each orbit,SMART-1 was in full sunlight and closeto the lunar surface. In that situation,the front sides of the solar wings wereheated by the Sun as the backsides wereexposed to a fully illuminated Moon.This caused the array temperature torise to potentially dangerous levels, toaround 97ºC – up to 10ºC higher thanpredicted.

Between 9 May and 13 June 2006, theFlight Control Team angled the solarwings 35º from the Sun, immediatelycooling the panels by 13ºC andeliminating the risk of damage, at theexpense of an 18% drop in powergeneration.

handed over to the Solar SystemsScience Operations Division, whoconverted it into a scientific lunarmission. The main instruments were:

– D-CIXS (Demonstration of aCompact X-ray Spectrometer): anX-ray spectrometer to investigate thecomposition of the Moon;

– AMIE: Advanced Moon Micro-

Imager. A miniaturised camera with a4-band filter;

– SIR: an infrared spectrometer tosearch for ice and make a mineral-ogical map.

The science phase began in March2005. The new orbit period, reduced to5 hours from around the 12 hoursoriginally planned, had major conse-quences for some of the ground systemsand the spacecraft. With more orbitrevolutions available, more scientificobservations could be made, so themission planning system had to beupgraded to cope with the increasednumber of commands (>2000/day onaverage) and data dumps. SMART’smemory stores, logic and distributionhad to be redesigned to cope with theincreased data load. All the payloadswere put together in a single memorystore, permitting the full automation ofall science data dumps. This ultimatelyled to a high degree of automation of allground and onboard operations: 70% ofthe ground station contact periods wereunmanned towards the end of themission.

Consideration of extending themission started soon after SMART-1was captured by the Moon. Severalstrategies and cases were evaluated,aiming at improving the scientificobservations during the extension. Thebest option could only be achieved byincreasing the ‘argument of perilune’(the position of the closest approach tothe Moon) to improve the illuminationconditions, coincidentally avoiding earlyimpact. This required using up theremaining xenon and giving up anyfurther control over the orbit for the restof the mission.

The manoeuvres began on 2 August2005 and continued through 207revolutions around the Moon, until17 September 2005. The ion thrustingrequired new procedures to use thexenon beyond the minimum residual of1.8 kg originally specified by themanufacturer. The last few days ofoperations consisted mainly of lettingthe almost empty high-pressure tank fill

Operations & Infrastructure

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 4140

SMART-1

Angling the solar wings 35º from the Sun solved the overheating problem. The vertical axis shows the array temperature in ºC

Nadir-pointing was not possible below 112 km

SMART-1 at the Moon. The left scale shows the distance from the Moon’s centre. The bottom of the white band shows the closestapproach each orbit (perilune); the top marks the highest (apolune)

SMART-1 spiralled down into its final orbit using its xenon thruster. The dotted parts of the curve show the thrust periods

The Moon was everywhere!Getting closer to impact, it becameincreasingly difficult to avoid violatingspacecraft rules. At low altitude, asSMART’s sky was filled by the Moon,pointing was a problem, as bothstartrackers were threatened withblinding.

Pointing at a fixed spot was no longerfeasible at altitudes below 240 kmbecause SMART could not turn fastenough. Nadir-pointing was no longerpossible below 112 km, because bothstartrackers had the surface in theirfields of view. This was finally solved bytilting SMART by 25º from nadir duringperilune passages.

Moon ImpactFrom the end of the reboost phase inSeptember 2005, SMART-1 was flyingaround the Moon without orbit control.The height of its closest approaches ()‘perilune’ was gradually falling asperturbations from Earth’s gravity tooktheir inevitable toll.

The orbit predictions carried out inearly 2006 indicated that impact wouldoccur on the far side by mid-August2006. The scientific community,interested in organising a campaign toobserve the impact, requested thatESOC and the Swedish Space Corpshould investigate ways to shift theimpact to the near side. This happened at

Moon Spiral: Distance from the Moon Centre

Dis

tan

ce f

rom

th

e M

oo

n C

en

tre

(k

m)

5.0x104

4.5x104

4.0x104

3.5x104

3.0x104

2.5x104

2.0x104

1.5x104

1.0x104

5.0x10-3

November 2004 December 2004 January 2005

Camino 8/1/07 5:08 PM Page 40

during the cruise from Earth saved5.5 kg of xenon, which could then beused to lower the highest point of theorbit (‘apolune’) from the planned10 000 km to 4600 km, improving theresolution of the science observations.

After achieving the primary goal oftesting and validating SMART-1’s newtechnologies – especially the electricpropulsion system – the mission was

up the downstream low-pressure tank toabout 2 bars, the bare minimum thatwas needed to fire the ion engine beforeit flamed out. The last pulse lasted just10 minutes before the engine flamed outfor the last time.

Science at the MoonAll of the scientific instruments werecalled upon during the observationphase. The team at the Science andTechnology Operations Centre atESTEC developed special tools to getthe most out of these observations.Most observations were done with theinstruments pointing towards theMoon’s centre, with the solar arraysquare-on to the Sun (‘nadir pointing’).Two special pointing modes could alsobe used for short periods: push-broomand target tracking.

In the push-broom mode, AMIE tooka sequence of images along the ground-track. Colour images were created bycombining the same scenes shot throughdifferent filters.

Occasionally, SMART-1 used target-tracking: as the craft travelled aroundthe Moon at several hundred metres persecond, AMIE was kept pointing at thesame target.

Solar array off-pointingAnalysis of the expected Moon impactby the Thermal & Structures Division atESTEC concluded that the solar arraytemperature could rise too high in May2006. For some time during each orbit,SMART-1 was in full sunlight and closeto the lunar surface. In that situation,the front sides of the solar wings wereheated by the Sun as the backsides wereexposed to a fully illuminated Moon.This caused the array temperature torise to potentially dangerous levels, toaround 97ºC – up to 10ºC higher thanpredicted.

Between 9 May and 13 June 2006, theFlight Control Team angled the solarwings 35º from the Sun, immediatelycooling the panels by 13ºC andeliminating the risk of damage, at theexpense of an 18% drop in powergeneration.

handed over to the Solar SystemsScience Operations Division, whoconverted it into a scientific lunarmission. The main instruments were:

– D-CIXS (Demonstration of aCompact X-ray Spectrometer): anX-ray spectrometer to investigate thecomposition of the Moon;

– AMIE: Advanced Moon Micro-

Imager. A miniaturised camera with a4-band filter;

– SIR: an infrared spectrometer tosearch for ice and make a mineral-ogical map.

The science phase began in March2005. The new orbit period, reduced to5 hours from around the 12 hoursoriginally planned, had major conse-quences for some of the ground systemsand the spacecraft. With more orbitrevolutions available, more scientificobservations could be made, so themission planning system had to beupgraded to cope with the increasednumber of commands (>2000/day onaverage) and data dumps. SMART’smemory stores, logic and distributionhad to be redesigned to cope with theincreased data load. All the payloadswere put together in a single memorystore, permitting the full automation ofall science data dumps. This ultimatelyled to a high degree of automation of allground and onboard operations: 70% ofthe ground station contact periods wereunmanned towards the end of themission.

Consideration of extending themission started soon after SMART-1was captured by the Moon. Severalstrategies and cases were evaluated,aiming at improving the scientificobservations during the extension. Thebest option could only be achieved byincreasing the ‘argument of perilune’(the position of the closest approach tothe Moon) to improve the illuminationconditions, coincidentally avoiding earlyimpact. This required using up theremaining xenon and giving up anyfurther control over the orbit for the restof the mission.

The manoeuvres began on 2 August2005 and continued through 207revolutions around the Moon, until17 September 2005. The ion thrustingrequired new procedures to use thexenon beyond the minimum residual of1.8 kg originally specified by themanufacturer. The last few days ofoperations consisted mainly of lettingthe almost empty high-pressure tank fill

Operations & Infrastructure

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 4140

SMART-1

Angling the solar wings 35º from the Sun solved the overheating problem. The vertical axis shows the array temperature in ºC

Nadir-pointing was not possible below 112 km

SMART-1 at the Moon. The left scale shows the distance from the Moon’s centre. The bottom of the white band shows the closestapproach each orbit (perilune); the top marks the highest (apolune)

SMART-1 spiralled down into its final orbit using its xenon thruster. The dotted parts of the curve show the thrust periods

The Moon was everywhere!Getting closer to impact, it becameincreasingly difficult to avoid violatingspacecraft rules. At low altitude, asSMART’s sky was filled by the Moon,pointing was a problem, as bothstartrackers were threatened withblinding.

Pointing at a fixed spot was no longerfeasible at altitudes below 240 kmbecause SMART could not turn fastenough. Nadir-pointing was no longerpossible below 112 km, because bothstartrackers had the surface in theirfields of view. This was finally solved bytilting SMART by 25º from nadir duringperilune passages.

Moon ImpactFrom the end of the reboost phase inSeptember 2005, SMART-1 was flyingaround the Moon without orbit control.The height of its closest approaches ()‘perilune’ was gradually falling asperturbations from Earth’s gravity tooktheir inevitable toll.

The orbit predictions carried out inearly 2006 indicated that impact wouldoccur on the far side by mid-August2006. The scientific community,interested in organising a campaign toobserve the impact, requested thatESOC and the Swedish Space Corpshould investigate ways to shift theimpact to the near side. This happened at

Moon Spiral: Distance from the Moon Centre

Dis

tan

ce f

rom

th

e M

oo

n C

en

tre

(k

m)

5.0x104

4.5x104

4.0x104

3.5x104

3.0x104

2.5x104

2.0x104

1.5x104

1.0x104

5.0x10-3

November 2004 December 2004 January 2005

Camino 8/1/07 5:08 PM Page 40

a stage when the ion engine had alreadyexhausted its fuel.

The question was how to obtain the~11.8 m/s change in velocity (‘delta-V’)to raise the orbit by just 90 km. The onlyoption was to use the attitude thrusters.Since SMART-1 was designed to bepropelled only by electric propulsion,the chemical thrusters were optimisedfor attitude control (by offloading theangular momentum built up in thereaction wheels).

The Flight Dynamics Team analysedthe possibility of harnessing the smalldelta-V incidentally produced by firingthe attitude thrusters as they offloadedthe reaction wheels. They finally cameup with a complex scheme involving aseries of offloadings around apolune,transferring SMART’s angular momen-tum from one side to the other, and viceversa. In between reaction wheeloffloadings, the craft would then beslewed such that the delta-V was alignedwith the flight direction. The overalleffect was the desired orbital change.

The attitude-thruster reboost phasestarted on 19 June 2006 and finished on2 July 2006. During 65 revolutionsaround the Moon, SMART-1performed seven wheel offloadings perorbit in the ~3 hours centred aroundapolune, accumulating 520 offloadings.

For comparison, a similar delta-Vwould require only a few minutes’ thrustby a satellite like Mars Express.

Approaching impactA week before impact, the MissionControl Team together with Industrydecided to take advantage of thefrequent startracker blindings by theMoon. The startrackers gathered some150 images between 12:15 and 13:06 UTon 1 September while going throughperilune (altitude ~12 km). The imageswere compiled into a movie that can beviewed at:

http://www.esa.int/SPECIALS/SMART-1/SEMZ16BVLRE_0.htmlhttp://esamultimedia.esa.int/multimedia/s m a r t - 1 / 0 6 0 9 0 1 _ S t a r t r a c k e r _Auto_Imaging_v4.wmv

The rim of Clausius CraterFor months, the best information theMission Control Team could obtainabout the surface in the impact area wasderived from the US Clementine lunarorbiter. This was initially used to selectthe impact date and time. Four daysbefore impact, the Flight Dynamics Team contacted Anthony Cook ofthe University of Nottingham (UK). Dr Cook, a specialist in 3-D digital image

interpretation and stereo image analysis,applied the SMART-1 orbit to his 3-Dtopographic model of the Moon – andobtained a surprising result. His analysisin cooperation with Mark Rosiek of theUS Geological Survey indicated a highprobability of hitting the rim of Clausius,a medium-sized crater at 43.5ºW/36.5ºSduring the perilune passage on thepenultimate orbit.

There was no time to confirm thisresult independently, so the MissionControl Team organised an internalmeeting to decide what to do. If Cookand Rosiek were right, then the impactwould occur an orbit earlier, jeopard-ising the observation campaign, unless alast-minute manoeuvre was done just2 days before expected impact. The riskwas that the orbit might be raised toomuch, causing the impact to occur anorbit later. It was a difficult dilemma,with a short time for a decision.

The Team gathered all the imagesalready taken by SMART-1 of thepotential impact area in order to correlatethem with the 3-D topography modelprovided by Cook and Rosiek. Thisexercise confirmed the topography of themodel. The Team accepted that the orbitcould intersect the rim of Clausius, as therim proved to be ~1500 m higher thanexpected from Clementine.

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 4342

SMART-1

SMART-1 might have hit crater Clausius

The impact area showing the last few orbits before and afterplanned impact. The trajectory (in blue) disappears where theorbit is below the surface. The last correction manoeuvreachieved its target, boosting perilune 592 m. (Topographic impactmodel by USGS/Univ. Nottingham)

The reboost strategy

Camino 8/1/07 5:08 PM Page 42

a stage when the ion engine had alreadyexhausted its fuel.

The question was how to obtain the~11.8 m/s change in velocity (‘delta-V’)to raise the orbit by just 90 km. The onlyoption was to use the attitude thrusters.Since SMART-1 was designed to bepropelled only by electric propulsion,the chemical thrusters were optimisedfor attitude control (by offloading theangular momentum built up in thereaction wheels).

The Flight Dynamics Team analysedthe possibility of harnessing the smalldelta-V incidentally produced by firingthe attitude thrusters as they offloadedthe reaction wheels. They finally cameup with a complex scheme involving aseries of offloadings around apolune,transferring SMART’s angular momen-tum from one side to the other, and viceversa. In between reaction wheeloffloadings, the craft would then beslewed such that the delta-V was alignedwith the flight direction. The overalleffect was the desired orbital change.

The attitude-thruster reboost phasestarted on 19 June 2006 and finished on2 July 2006. During 65 revolutionsaround the Moon, SMART-1performed seven wheel offloadings perorbit in the ~3 hours centred aroundapolune, accumulating 520 offloadings.

For comparison, a similar delta-Vwould require only a few minutes’ thrustby a satellite like Mars Express.

Approaching impactA week before impact, the MissionControl Team together with Industrydecided to take advantage of thefrequent startracker blindings by theMoon. The startrackers gathered some150 images between 12:15 and 13:06 UTon 1 September while going throughperilune (altitude ~12 km). The imageswere compiled into a movie that can beviewed at:

http://www.esa.int/SPECIALS/SMART-1/SEMZ16BVLRE_0.htmlhttp://esamultimedia.esa.int/multimedia/s m a r t - 1 / 0 6 0 9 0 1 _ S t a r t r a c k e r _Auto_Imaging_v4.wmv

The rim of Clausius CraterFor months, the best information theMission Control Team could obtainabout the surface in the impact area wasderived from the US Clementine lunarorbiter. This was initially used to selectthe impact date and time. Four daysbefore impact, the Flight Dynamics Team contacted Anthony Cook ofthe University of Nottingham (UK). Dr Cook, a specialist in 3-D digital image

interpretation and stereo image analysis,applied the SMART-1 orbit to his 3-Dtopographic model of the Moon – andobtained a surprising result. His analysisin cooperation with Mark Rosiek of theUS Geological Survey indicated a highprobability of hitting the rim of Clausius,a medium-sized crater at 43.5ºW/36.5ºSduring the perilune passage on thepenultimate orbit.

There was no time to confirm thisresult independently, so the MissionControl Team organised an internalmeeting to decide what to do. If Cookand Rosiek were right, then the impactwould occur an orbit earlier, jeopard-ising the observation campaign, unless alast-minute manoeuvre was done just2 days before expected impact. The riskwas that the orbit might be raised toomuch, causing the impact to occur anorbit later. It was a difficult dilemma,with a short time for a decision.

The Team gathered all the imagesalready taken by SMART-1 of thepotential impact area in order to correlatethem with the 3-D topography modelprovided by Cook and Rosiek. Thisexercise confirmed the topography of themodel. The Team accepted that the orbitcould intersect the rim of Clausius, as therim proved to be ~1500 m higher thanexpected from Clementine.

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 4342

SMART-1

SMART-1 might have hit crater Clausius

The impact area showing the last few orbits before and afterplanned impact. The trajectory (in blue) disappears where theorbit is below the surface. The last correction manoeuvreachieved its target, boosting perilune 592 m. (Topographic impactmodel by USGS/Univ. Nottingham)

The reboost strategy

Camino 8/1/07 5:08 PM Page 42

The decision was to maximise theprobability of impacting as plannedduring the morning of 3 September. Asa result, during the night of 1–2 Sept-ember, the controllers had to make a lastcorrection manoeuvre to boost thepenultimate perilune by a mere 600 m;592 m was achieved.

Impact observationsImpact was now expected on the Moon’snear side, in a dark area close to theterminator (the line separating day fromnight), at a grazing angle of 5–10º and aspeed of ~2 km/s. The time and locationwere planned to favour observations ofthe event from telescopes on Earth.

The predicted effects included athermal flash and possible fireball fromthe leftover hydrazine fuel aboard

before the impact. The team set upanother big screen showing thetelemetry scrolling down in real time. Onboth sides of the room, two large clocksdisplayed the count down.

A growing buzz of excitement tookover the room as impact timeapproached. Starting at 17 s, everyone inthe room found themselves chorusingthe countdown – just as was done for thebirth of the mission some 3 years before.

The freeze of the scrolling telemetryjust a second after zero left everyone inthe room in static silence for a fewseconds until somebody broke the silencewith applause that was joined in by all.

The mission team and the journalistshad a few seconds to relax before all eyeswent back to the main wall screen, now

SMART-1, a crater perhaps 5–10 macross, and dust and other ejectedmaterial travelling some distance acrossthe surface.

The observation campaign counted onprofessional and amateur observersworldwide, including South Africa, theCanary Islands, South America and theUSA. It involved a core of participatingtelescopes, including: the South AfricanLarge Telescope (SALT), the Calar Altoobservatory in Andalucía (E), the ESAOptical Ground Station on Tenerife (E),the CEA Cariri observatory in Brazil,the Argentina National Telescope, the Canada-France-Hawaii Telescope(CFHT), the Japanese Subaru Auxiliarytelescopes on Hawaii, and Sweden’sOdin satellite.

Five radio telescopes were coordina-ted by the Joint Institute for VLBI (Very Long Baseline Interferometry) in Europe (JIVE): the Medicina 32 mantenna in Italy, the Fortaleza 14 mantenna in Brazil, the German-ChileanTIGO 6 m antenna in Chile, the Mount Pleasant Observatory of theUniversity of Tasmania (Australia) and the Australia Telescope CompactArray.

With the impact calculated to be at05:42 UT, observers from North andSouth America and the East Pacificwould be able to see it at night. The bestview would be from the US west coast,Hawaii and the East Pacific.

but also fulfilled all of its secondaryobjectives in technology demonstrationand science.

ESA gained valuable expertise innavigation techniques using low-thrustpropulsion. The procedures used toexhaust the xenon fuel and the use ofattitude thrusters to generate delta-Vwere a first for ESA. Similarly, groundoperations experimented with innovativecost-effective operational concepts, suchas reduced-staff spacecraft controlling,distribution of spacecraft housekeepingtelemetry via the internet and a highlevel of automated operations.

In addition, SMART-1 sparkedunexpected interest in international andcross-agency cooperation in areas such asground station support (with Germany);tracking co-targeting and Moonexploration cooperation (with China andIndia); and VLBI science and Ka-bandexperiments (with NASA). In view of therecent plans for future scientific andhuman missions to the Moon by severalagencies, SMART-1 can be seen as apathfinder for renewed lunar exploration.

For the Mission Control Team, theend brought mixed feelings: thesatisfaction of having accomplished acomplex mission, but sadness in seeingthe end of an adventure. All of thoseinvolved are looking forward to newadventures at the Moon and elsewhere inthe Solar System. e

The impactOn 3 September, early in the morning,the SMART-1 team had to face anotherlast-minute contingency: the servo-drivers of ESA’s antenna in New Norcia,Australia, signalled a problem and therewas nothing that could be doneremotely to resolve it. While an engineerwas telephoned to drive from Perth toNew Norcia as fast as possible, theFlight Control Team started developinga contingency procedure using the Perthantenna with the New Norcia antennain fixed pointing. Fortunately, by thetime journalists started gathering behindthe glass wall of the ESOC’s MainControl Room, the problem had beenresolved at the station.

A wall screen displayed the last eventsprogrammed on board for execution

Operations & Infrastructure

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 4544

SMART-1

SMART-1 strikes the Moon. (CFHT)Brightness contours of the impact flash. (CFHT)The lunar impact of SMART-1. (CFHT)

The impact site as viewed from Earth The flash and dust cloud following impact (CFHT)

showing the images being received fromthe Canada-France-Hawaii Telescope.The telescope, equipped with a newinfrared mosaic camera, suddenlyoffered a stunning image of theSMART-1 impact, a very bright flash onthe dim landscape lit by earthshine. Theimage was made available to ESA andthe world via the internet just momentsafter SMART-1 radio silence had madeclear that the mission had ended.

From a detailed analysis of the CFHTinfrared movie, a cloud of ejectatravelling some 80 km in about 130 s wasreported by Christian Veillet.

The last signal, from SMART-1’sKaTE/Ka-band experiment, was receivedon Earth at 05:42:25 UT, through theNASA Deep Space Network radiostation DSS13 in the California desert.

CSIRO, TIGO and the MountPleasant Observatory all heard the finalsignal. The radio observations weredone with very high accuracy; SMART-1sent its last signals to Earth at05:42:21:759 UT. These times were inclose agreement with the last flightdynamics prediction of 05:42:20 UT,and with the last telemetry framereceived at ESOC through New Norcia.

ConclusionsSMART-1 not only achieved its primaryobjective of validating the use of electricpropulsion for interplanetary missions,

Camino 8/1/07 5:08 PM Page 44

The decision was to maximise theprobability of impacting as plannedduring the morning of 3 September. Asa result, during the night of 1–2 Sept-ember, the controllers had to make a lastcorrection manoeuvre to boost thepenultimate perilune by a mere 600 m;592 m was achieved.

Impact observationsImpact was now expected on the Moon’snear side, in a dark area close to theterminator (the line separating day fromnight), at a grazing angle of 5–10º and aspeed of ~2 km/s. The time and locationwere planned to favour observations ofthe event from telescopes on Earth.

The predicted effects included athermal flash and possible fireball fromthe leftover hydrazine fuel aboard

before the impact. The team set upanother big screen showing thetelemetry scrolling down in real time. Onboth sides of the room, two large clocksdisplayed the count down.

A growing buzz of excitement tookover the room as impact timeapproached. Starting at 17 s, everyone inthe room found themselves chorusingthe countdown – just as was done for thebirth of the mission some 3 years before.

The freeze of the scrolling telemetryjust a second after zero left everyone inthe room in static silence for a fewseconds until somebody broke the silencewith applause that was joined in by all.

The mission team and the journalistshad a few seconds to relax before all eyeswent back to the main wall screen, now

SMART-1, a crater perhaps 5–10 macross, and dust and other ejectedmaterial travelling some distance acrossthe surface.

The observation campaign counted onprofessional and amateur observersworldwide, including South Africa, theCanary Islands, South America and theUSA. It involved a core of participatingtelescopes, including: the South AfricanLarge Telescope (SALT), the Calar Altoobservatory in Andalucía (E), the ESAOptical Ground Station on Tenerife (E),the CEA Cariri observatory in Brazil,the Argentina National Telescope, the Canada-France-Hawaii Telescope(CFHT), the Japanese Subaru Auxiliarytelescopes on Hawaii, and Sweden’sOdin satellite.

Five radio telescopes were coordina-ted by the Joint Institute for VLBI (Very Long Baseline Interferometry) in Europe (JIVE): the Medicina 32 mantenna in Italy, the Fortaleza 14 mantenna in Brazil, the German-ChileanTIGO 6 m antenna in Chile, the Mount Pleasant Observatory of theUniversity of Tasmania (Australia) and the Australia Telescope CompactArray.

With the impact calculated to be at05:42 UT, observers from North andSouth America and the East Pacificwould be able to see it at night. The bestview would be from the US west coast,Hawaii and the East Pacific.

but also fulfilled all of its secondaryobjectives in technology demonstrationand science.

ESA gained valuable expertise innavigation techniques using low-thrustpropulsion. The procedures used toexhaust the xenon fuel and the use ofattitude thrusters to generate delta-Vwere a first for ESA. Similarly, groundoperations experimented with innovativecost-effective operational concepts, suchas reduced-staff spacecraft controlling,distribution of spacecraft housekeepingtelemetry via the internet and a highlevel of automated operations.

In addition, SMART-1 sparkedunexpected interest in international andcross-agency cooperation in areas such asground station support (with Germany);tracking co-targeting and Moonexploration cooperation (with China andIndia); and VLBI science and Ka-bandexperiments (with NASA). In view of therecent plans for future scientific andhuman missions to the Moon by severalagencies, SMART-1 can be seen as apathfinder for renewed lunar exploration.

For the Mission Control Team, theend brought mixed feelings: thesatisfaction of having accomplished acomplex mission, but sadness in seeingthe end of an adventure. All of thoseinvolved are looking forward to newadventures at the Moon and elsewhere inthe Solar System. e

The impactOn 3 September, early in the morning,the SMART-1 team had to face anotherlast-minute contingency: the servo-drivers of ESA’s antenna in New Norcia,Australia, signalled a problem and therewas nothing that could be doneremotely to resolve it. While an engineerwas telephoned to drive from Perth toNew Norcia as fast as possible, theFlight Control Team started developinga contingency procedure using the Perthantenna with the New Norcia antennain fixed pointing. Fortunately, by thetime journalists started gathering behindthe glass wall of the ESOC’s MainControl Room, the problem had beenresolved at the station.

A wall screen displayed the last eventsprogrammed on board for execution

Operations & Infrastructure

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 4544

SMART-1

SMART-1 strikes the Moon. (CFHT)Brightness contours of the impact flash. (CFHT)The lunar impact of SMART-1. (CFHT)

The impact site as viewed from Earth The flash and dust cloud following impact (CFHT)

showing the images being received fromthe Canada-France-Hawaii Telescope.The telescope, equipped with a newinfrared mosaic camera, suddenlyoffered a stunning image of theSMART-1 impact, a very bright flash onthe dim landscape lit by earthshine. Theimage was made available to ESA andthe world via the internet just momentsafter SMART-1 radio silence had madeclear that the mission had ended.

From a detailed analysis of the CFHTinfrared movie, a cloud of ejectatravelling some 80 km in about 130 s wasreported by Christian Veillet.

The last signal, from SMART-1’sKaTE/Ka-band experiment, was receivedon Earth at 05:42:25 UT, through theNASA Deep Space Network radiostation DSS13 in the California desert.

CSIRO, TIGO and the MountPleasant Observatory all heard the finalsignal. The radio observations weredone with very high accuracy; SMART-1sent its last signals to Earth at05:42:21:759 UT. These times were inclose agreement with the last flightdynamics prediction of 05:42:20 UT,and with the last telemetry framereceived at ESOC through New Norcia.

ConclusionsSMART-1 not only achieved its primaryobjective of validating the use of electricpropulsion for interplanetary missions,

Camino 8/1/07 5:08 PM Page 44

Solar Arrays

Funded by ESA’s Advanced Research in

lTelecommunications (ARTES) programme,Thales Alenia Space has developed a new

generation of high-power ultra-lightweightsolar arrays for telecommunications satellites.Thanks to close cooperation with its industrialpartners in Europe, the company has genericallyqualified a solar array io meet market needs.Indeed, three flight projects were already usingthe new design as qualification was completed.In addition, the excellent mechanical andthermal behaviour of the new panel structureare contributing to other missions such asPleïades and LISA Pathfinder.

IntroductionThe standard ‘Solarbus’ solar array ofThales Alenia Space for the Spacebustelecommunications satellite platformwas designed in 1998. The flight-proventechnology deploys modular panels,using patented frictionless hinges, toprovide up to 13 kW end-of-life (EOL)power with an EOL power-to-mass ratioof 48–50 W/kg, the best now available.

Thanks to the close cooperation withthe Spacebus satellite team, exactly thesame design has been used for all of the

Freddy GeyerProgramme Manager, Thales Alenia Space,Cannes, France

Doug CaswellARTES Project Manager, Directorate ofTelecommunication & Navigation, ESTEC,Noordwijk, The Netherlands

Carla SignoriniHead of the Power and Energy ConversionDivision, Directorate of Technical and QualityManagement, ESTEC, Noordwijk,The Netherlands

esa bulletin 131 - august 2007 47

Powering the FutureA New Generation of

High-Performance Solar Arrays

caswell 8/1/07 5:09 PM Page 46

Solar Arrays

Funded by ESA’s Advanced Research in

lTelecommunications (ARTES) programme,Thales Alenia Space has developed a new

generation of high-power ultra-lightweightsolar arrays for telecommunications satellites.Thanks to close cooperation with its industrialpartners in Europe, the company has genericallyqualified a solar array io meet market needs.Indeed, three flight projects were already usingthe new design as qualification was completed.In addition, the excellent mechanical andthermal behaviour of the new panel structureare contributing to other missions such asPleïades and LISA Pathfinder.

IntroductionThe standard ‘Solarbus’ solar array ofThales Alenia Space for the Spacebustelecommunications satellite platformwas designed in 1998. The flight-proventechnology deploys modular panels,using patented frictionless hinges, toprovide up to 13 kW end-of-life (EOL)power with an EOL power-to-mass ratioof 48–50 W/kg, the best now available.

Thanks to the close cooperation withthe Spacebus satellite team, exactly thesame design has been used for all of the

Freddy GeyerProgramme Manager, Thales Alenia Space,Cannes, France

Doug CaswellARTES Project Manager, Directorate ofTelecommunication & Navigation, ESTEC,Noordwijk, The Netherlands

Carla SignoriniHead of the Power and Energy ConversionDivision, Directorate of Technical and QualityManagement, ESTEC, Noordwijk,The Netherlands

esa bulletin 131 - august 2007 47

Powering the FutureA New Generation of

High-Performance Solar Arrays

caswell 8/1/07 5:09 PM Page 46

solar array panels: more than 150identical panels have been producedover the last 5 years.

Now, to satisfy growing marketdemands, a new-generation design hasbeen developed to provide more then15 kW power EOL in a 7-panel version.In addition, a new Lightweight PanelStructure (LPS) has been introduced toincrease the solar array W/kg and thusmaintain the competitiveness of Space-bus in the commercial market.

2004 was a particularly bad year in thetelecommunications business: half ofthe insurance payouts stemmed fromsolar array problems in space (fromother suppliers!). This confirmed thatproducts as critical as solar arrays mustbe robustly developed to ensure highreliability.

Robust and exhaustive development ismandatory but not compatible withflight schedules. In fact, as the marketbecomes more aggressive, the manufac-turing cycles are being more tightlysqueezed. The conclusion is thatdevelopment must be done outside offlight programmes. This requires‘generic’ development to ensure theproduct is ready for the market beforethe first missions requires it.

Development Based on Design HeritageThe overall goal of this huge develop-ment effort is that the optimisedmechanical structure will supportcontinuous improvements in the electricalarchitecture over the next 10 years. Afterthis robust generic development, proto-flight qualification will be provided bythe first flight project.

Design targetsThe new design is based on the fact that,during the three major life phases of asolar array (launch, deployment andorbital life), the structural needs of thecentral panels are more important thanfor the lateral panels. The novelty of theLPS design rests on this difference,allowing the lateral panels to be half asthick as the central panels.

A central mast has a yoke plus two,three or four central panels. When morepower is needed, lateral panels areadded. The stowed configuration is thekey to this innovative design. The panels

Guidelines for Generic DevelopementThe development of Thales Alenia’sgeneric new-generation high-powersolar array began in 2002 underguidelines that came directly fromcustomers. Customers are sensitive ontwo main requirements that are difficultto test on the ground: safe deploymentin orbit, and production of the requiredpower during the 15-year lifetime.

Safe deployment is ensured by detaileddynamic analysis correlated with theflight experience of numerous identicalsolar arrays, together with the use of‘lateral’ panels with the frictionless Adele

are stacked at launch so that the ultra-thin lateral panels are protected betweentwo ‘structural’ central panels. Shimskeep the launch loads away from thelateral panels.

This approach allows several config-urations, with two or three panels in lineand zero to six lateral panels.

Step-by-Step validationQualification was achieved using a step-by-step approach that limited the riskduring the programme. The first testcampaign characterised the shims’dynamic behaviour during launch. Asecond text validated the load paththrough the shims, tuned the shims andvalidated the model’s stiffness linearity.

Thanks to these two main tests at thestart of the development process, it waspossible to model the shim character-istics and to build a global mathematicalmodel that represents the entire solarwing. Using this model, a detailedanalysis was performed to size the new

substrates and the mechanical architec-ture of the 4–10-panel wing configura-tions.

Additional intermediate tests wereperformed on half-scale panels to verifyearly on the integrity of the solar cellsafter the vibration tests.

In addition, new manufacturing pro-cesses were developed for the light-weight panels, together with a robustdatabase for mechanical and thermaldesign. Compatibility with all cell andbonding processes were verified vialifecycle testing. Finally, full-scale panelsequipped with GaAs, silicon cells andrepresentative cell dummies were subjec-ted to thermal vacuum cycling.

In addition, the full Assembly, Inte-gration and Test sequence was validated.

ConclusionThe first two steps of this developmentprogramme are completed. Threecommercial flight projects are alreadyrunning using silicon high-efficiencycells for 15 kW EOL power. The use ofGaAs cells is then foreseen to providemore power or reduce the number ofpanels. GaAs cells will allow the LPSarchitecture to satisfy future marketneeds easily. It will be possible to reach23–29 kW BOL in a 7-panel configura-tion; more can be achieved because theLPS design offers 10 panels per wing.

e

hinges flown in several programmessince 1998. Using only flight-provensolar cells satisfies the electrical aspects.

Meeting Power Growth Needs Usually, power growth is achieved byincreasing the efficiency of the solarcells. This is how the 13% efficiency ofstandard silicon cells has grown totoday’s 28% for triple-junction galliumarsenide (GaAs) cells. More then 30%efficiency is expected in the near futurefor GaAs.

However, improving the power-to-mass ratio also calls for redesigning themechanical and electrical architectures.

The mechanical improvement is in linewith the logic of 1998: a standardmodular panel multiplied to provide thedesired area. The new array has sevenpanels per wing as the baseline, butoffers a growth potential to a 10-panelversion. Thanks to the novel way thearray is stowed, non-structural ultra-thin lateral panels can be used. No othersolar array does this.

Different cell technologies will copewith the power demand:

– for the near-term 15 kW EOL, thinhigh-efficiency silicon cells will beused for the first missions;

– GaAs cells will be called on in asecond step if more power is needed;

– design novelties already under devel-opment will make the design moreattractive.

Telecommunication & Navigation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 4948

Solar Arrays

Preparing for the acoustic vibration test to simulate the rigours oflaunch

Vibration test of a folded array, with two ultra-thin panels sandwiched between standard panels for protection

Preparing a full-scale panel for thermal-vacuum tests

Possible configurations of the new solar array

The new Solarbus array (top right) has been added to the range. The ‘lateral’ panels unfold from the central panels

Thales Alenia Space Background and heritage:

power range starting from 160W using Silicon or GaAs technology

kW

EO

L

15

13

10.5

Ordered or produced

In flight

8

3.6

1.5

0.15

caswell 8/1/07 5:09 PM Page 48

solar array panels: more than 150identical panels have been producedover the last 5 years.

Now, to satisfy growing marketdemands, a new-generation design hasbeen developed to provide more then15 kW power EOL in a 7-panel version.In addition, a new Lightweight PanelStructure (LPS) has been introduced toincrease the solar array W/kg and thusmaintain the competitiveness of Space-bus in the commercial market.

2004 was a particularly bad year in thetelecommunications business: half ofthe insurance payouts stemmed fromsolar array problems in space (fromother suppliers!). This confirmed thatproducts as critical as solar arrays mustbe robustly developed to ensure highreliability.

Robust and exhaustive development ismandatory but not compatible withflight schedules. In fact, as the marketbecomes more aggressive, the manufac-turing cycles are being more tightlysqueezed. The conclusion is thatdevelopment must be done outside offlight programmes. This requires‘generic’ development to ensure theproduct is ready for the market beforethe first missions requires it.

Development Based on Design HeritageThe overall goal of this huge develop-ment effort is that the optimisedmechanical structure will supportcontinuous improvements in the electricalarchitecture over the next 10 years. Afterthis robust generic development, proto-flight qualification will be provided bythe first flight project.

Design targetsThe new design is based on the fact that,during the three major life phases of asolar array (launch, deployment andorbital life), the structural needs of thecentral panels are more important thanfor the lateral panels. The novelty of theLPS design rests on this difference,allowing the lateral panels to be half asthick as the central panels.

A central mast has a yoke plus two,three or four central panels. When morepower is needed, lateral panels areadded. The stowed configuration is thekey to this innovative design. The panels

Guidelines for Generic DevelopementThe development of Thales Alenia’sgeneric new-generation high-powersolar array began in 2002 underguidelines that came directly fromcustomers. Customers are sensitive ontwo main requirements that are difficultto test on the ground: safe deploymentin orbit, and production of the requiredpower during the 15-year lifetime.

Safe deployment is ensured by detaileddynamic analysis correlated with theflight experience of numerous identicalsolar arrays, together with the use of‘lateral’ panels with the frictionless Adele

are stacked at launch so that the ultra-thin lateral panels are protected betweentwo ‘structural’ central panels. Shimskeep the launch loads away from thelateral panels.

This approach allows several config-urations, with two or three panels in lineand zero to six lateral panels.

Step-by-Step validationQualification was achieved using a step-by-step approach that limited the riskduring the programme. The first testcampaign characterised the shims’dynamic behaviour during launch. Asecond text validated the load paththrough the shims, tuned the shims andvalidated the model’s stiffness linearity.

Thanks to these two main tests at thestart of the development process, it waspossible to model the shim character-istics and to build a global mathematicalmodel that represents the entire solarwing. Using this model, a detailedanalysis was performed to size the new

substrates and the mechanical architec-ture of the 4–10-panel wing configura-tions.

Additional intermediate tests wereperformed on half-scale panels to verifyearly on the integrity of the solar cellsafter the vibration tests.

In addition, new manufacturing pro-cesses were developed for the light-weight panels, together with a robustdatabase for mechanical and thermaldesign. Compatibility with all cell andbonding processes were verified vialifecycle testing. Finally, full-scale panelsequipped with GaAs, silicon cells andrepresentative cell dummies were subjec-ted to thermal vacuum cycling.

In addition, the full Assembly, Inte-gration and Test sequence was validated.

ConclusionThe first two steps of this developmentprogramme are completed. Threecommercial flight projects are alreadyrunning using silicon high-efficiencycells for 15 kW EOL power. The use ofGaAs cells is then foreseen to providemore power or reduce the number ofpanels. GaAs cells will allow the LPSarchitecture to satisfy future marketneeds easily. It will be possible to reach23–29 kW BOL in a 7-panel configura-tion; more can be achieved because theLPS design offers 10 panels per wing.

e

hinges flown in several programmessince 1998. Using only flight-provensolar cells satisfies the electrical aspects.

Meeting Power Growth Needs Usually, power growth is achieved byincreasing the efficiency of the solarcells. This is how the 13% efficiency ofstandard silicon cells has grown totoday’s 28% for triple-junction galliumarsenide (GaAs) cells. More then 30%efficiency is expected in the near futurefor GaAs.

However, improving the power-to-mass ratio also calls for redesigning themechanical and electrical architectures.

The mechanical improvement is in linewith the logic of 1998: a standardmodular panel multiplied to provide thedesired area. The new array has sevenpanels per wing as the baseline, butoffers a growth potential to a 10-panelversion. Thanks to the novel way thearray is stowed, non-structural ultra-thin lateral panels can be used. No othersolar array does this.

Different cell technologies will copewith the power demand:

– for the near-term 15 kW EOL, thinhigh-efficiency silicon cells will beused for the first missions;

– GaAs cells will be called on in asecond step if more power is needed;

– design novelties already under devel-opment will make the design moreattractive.

Telecommunication & Navigation

esa bulletin 131 - august 2007esa bulletin 131 - august 2007 www.esa.intwww.esa.int 4948

Solar Arrays

Preparing for the acoustic vibration test to simulate the rigours oflaunch

Vibration test of a folded array, with two ultra-thin panels sandwiched between standard panels for protection

Preparing a full-scale panel for thermal-vacuum tests

Possible configurations of the new solar array

The new Solarbus array (top right) has been added to the range. The ‘lateral’ panels unfold from the central panels

Thales Alenia Space Background and heritage:

power range starting from 160W using Silicon or GaAs technology

kW

EO

L

15

13

10.5

Ordered or produced

In flight

8

3.6

1.5

0.15

caswell 8/1/07 5:09 PM Page 48

esa bulletin 131 - august 2007www.esa.int 51

In ProgressProgrammes

50 esa bulletin 131 - august 2007 www.esa.int

LAUNCHED APRIL1990

LAUNCHED OCTOBER 1990

LAUNCHED DECEMBER 1995

LAUNCHED OCTOBER 1997

LAUNCHED DECEMBER 1999

RE-LAUNCHED MID-2000

LAUNCHED OCTOBER 2002

LAUNCHED JUNE 2003

LAUNCHED SEPTEMBER 2003

TC-1 LAUNCHED DECEMBER. 2003TC-2 LAUNCHED JULY 2004LAUNCHED MARCH 2004

LAUNCHED NOVEMBER 2005

LAUNCH JULY 2008

LAUNCH 1st QUARTER 2010

LAUNCH END-2011

LAUNCH JUNE 2013

LAUNCH AUGUST 2013

M5 LAUNCHED 1991, M6 1993, M7 1997

LAUNCHED APRIL 1995

LAUNCHED MARCH 2002

MSG-3 LAUNCH 2011, MSG-4 LAUNCH 2013

METOP-A LAUNCH OCTOBER 2006,METOP-B 2010, METOP-C 2015LAUNCH FAILURE OCTOBER 2005CRYOSAT-2 LAUNCH MARCH 2009

GIOVE-A LAUNCHED DEC. 2005GIOVE-B LAUNCH END-2007, IOV 2009

LAUNCH END-FEBRUARY 2008

LAUNCH MAY 2008

LAUNCH JUNE 2009

LAUNCH 2010

LAUNCH END-2012

LAUNCHED JULY 2001

LAUNCH 2011

OPERATIONS START 2007

LAUNCH END-2010

LAUNCHED OCTOBER 2001

LAUNCH MAY 2008

LAUNCHED FEBRUARY 2005

LAUNCH DECEMBER 2007

FIRST LAUNCH JANUARY 2008

LAUNCHES OCTOBER 2007 & APRIL 2010CUPOLA WITH NODE-3LAUNCH NOT BEFORE END-2009

EDR/EUTEF/SOLAR WITH COLUMBUS

BIO, FSL, EPM with COLUMBUS

OPERATIONAL

FIRST LAUNCH SEPTEMBER 2008

READY FOR LAUNCH DECEMBER 2008

2001 2002 2003 2004 2005 2006 2007 2008 2009J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND COMMENTS

SPACE TELESCOPE

ULYSSES

SOHO

HUYGENS

XMM-NEWTON

CLUSTER

INTEGRAL

MARS EXPRESS

SMART-1

DOUBLE STAR

ROSETTA

VENUS EXPRESS

HERSCHEL/PLANCK

LISA PATHFINDER

GAIA

JWST

BEPICOLOMBO

METEOSAT-5/6/7

ERS-2

ENVISAT

MSG

METOP

CRYOSAT

GOCE

SMOS

ADM-AEOLUS

SWARM

EARTHCARE

ARTEMIS

ALPHABUS

GNSS-1/EGNOS

SMALL GEO SAT.

GALILEOSAT

PROBA-1

PROBA-2

SLOSHSAT

COLUMBUS

ATV

NODE-2 & -3 & CUPOLA

ERA

ISS BARTER & UTIL. PREP.

EMIR/ELIPS

MFC

ASTRONAUT FLT.

ARIANE-5

VEGA

SOYUZ AT CSG

LAUNCH MID-2013

AURORA CORE

EXOMARS

PROJECT

SCIE

NTI

FIC

PRO

GR

AMM

EEA

RTH

OBS

ERVA

TIO

NPR

OG

RAM

ME

TEC

HN

OL.

PRO

G.

CO

MM

S./N

AV.

PRO

GR

AMM

EH

UM

AN S

PAC

EFLI

GH

T, M

ICR

OG

RAV

ITY

& EX

PLO

RAT

ION

PR

OG

RAM

ME

LAU

NC

HER

PRO

G.

APCF-6/BIOBOX-5/ARMS/BIOPACK/FAST-2/ERISTO

MATROSHKAFOTON-MI

PCDF

TEXUS-44/45 MARESMAXUS-8

MSG

MSG-1 MSG-2

MELFI 1 MELFI 2

GIOVE-A GIOVE-B

EDR/EUTEF/SOLAR

MAXUS-6 EMCS/PEMS

FOTON-M2EML-1PFS

FOTON-M3

TEXUS-42

MSL

MASER-10

DEFINITION PHASE

OPERATIONS

MAIN DEVELOPMENT PHASE

ADDITIONAL LIFE POSSIBLELAUNCH/READY FOR LAUNCH

STORAGE

MASER-11MAXUS-7/TEXUS-43TEXUS-46

Programmes

in ProgressStatus end-June 2007

BPb131.qxd 8/1/07 5:10 PM Page 50

esa bulletin 131 - august 2007www.esa.int 51

In ProgressProgrammes

50 esa bulletin 131 - august 2007 www.esa.int

LAUNCHED APRIL1990

LAUNCHED OCTOBER 1990

LAUNCHED DECEMBER 1995

LAUNCHED OCTOBER 1997

LAUNCHED DECEMBER 1999

RE-LAUNCHED MID-2000

LAUNCHED OCTOBER 2002

LAUNCHED JUNE 2003

LAUNCHED SEPTEMBER 2003

TC-1 LAUNCHED DECEMBER. 2003TC-2 LAUNCHED JULY 2004LAUNCHED MARCH 2004

LAUNCHED NOVEMBER 2005

LAUNCH JULY 2008

LAUNCH 1st QUARTER 2010

LAUNCH END-2011

LAUNCH JUNE 2013

LAUNCH AUGUST 2013

M5 LAUNCHED 1991, M6 1993, M7 1997

LAUNCHED APRIL 1995

LAUNCHED MARCH 2002

MSG-3 LAUNCH 2011, MSG-4 LAUNCH 2013

METOP-A LAUNCH OCTOBER 2006,METOP-B 2010, METOP-C 2015LAUNCH FAILURE OCTOBER 2005CRYOSAT-2 LAUNCH MARCH 2009

GIOVE-A LAUNCHED DEC. 2005GIOVE-B LAUNCH END-2007, IOV 2009

LAUNCH END-FEBRUARY 2008

LAUNCH MAY 2008

LAUNCH JUNE 2009

LAUNCH 2010

LAUNCH END-2012

LAUNCHED JULY 2001

LAUNCH 2011

OPERATIONS START 2007

LAUNCH END-2010

LAUNCHED OCTOBER 2001

LAUNCH MAY 2008

LAUNCHED FEBRUARY 2005

LAUNCH DECEMBER 2007

FIRST LAUNCH JANUARY 2008

LAUNCHES OCTOBER 2007 & APRIL 2010CUPOLA WITH NODE-3LAUNCH NOT BEFORE END-2009

EDR/EUTEF/SOLAR WITH COLUMBUS

BIO, FSL, EPM with COLUMBUS

OPERATIONAL

FIRST LAUNCH SEPTEMBER 2008

READY FOR LAUNCH DECEMBER 2008

2001 2002 2003 2004 2005 2006 2007 2008 2009J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND J FMAM J J A SOND COMMENTS

SPACE TELESCOPE

ULYSSES

SOHO

HUYGENS

XMM-NEWTON

CLUSTER

INTEGRAL

MARS EXPRESS

SMART-1

DOUBLE STAR

ROSETTA

VENUS EXPRESS

HERSCHEL/PLANCK

LISA PATHFINDER

GAIA

JWST

BEPICOLOMBO

METEOSAT-5/6/7

ERS-2

ENVISAT

MSG

METOP

CRYOSAT

GOCE

SMOS

ADM-AEOLUS

SWARM

EARTHCARE

ARTEMIS

ALPHABUS

GNSS-1/EGNOS

SMALL GEO SAT.

GALILEOSAT

PROBA-1

PROBA-2

SLOSHSAT

COLUMBUS

ATV

NODE-2 & -3 & CUPOLA

ERA

ISS BARTER & UTIL. PREP.

EMIR/ELIPS

MFC

ASTRONAUT FLT.

ARIANE-5

VEGA

SOYUZ AT CSG

LAUNCH MID-2013

AURORA CORE

EXOMARS

PROJECT

SCIE

NTI

FIC

PRO

GR

AMM

EEA

RTH

OBS

ERVA

TIO

NPR

OG

RAM

ME

TEC

HN

OL.

PRO

G.

CO

MM

S./N

AV.

PRO

GR

AMM

EH

UM

AN S

PAC

EFLI

GH

T, M

ICR

OG

RAV

ITY

& EX

PLO

RAT

ION

PR

OG

RAM

ME

LAU

NC

HER

PRO

G.

APCF-6/BIOBOX-5/ARMS/BIOPACK/FAST-2/ERISTO

MATROSHKAFOTON-MI

PCDF

TEXUS-44/45 MARESMAXUS-8

MSG

MSG-1 MSG-2

MELFI 1 MELFI 2

GIOVE-A GIOVE-B

EDR/EUTEF/SOLAR

MAXUS-6 EMCS/PEMS

FOTON-M2EML-1PFS

FOTON-M3

TEXUS-42

MSL

MASER-10

DEFINITION PHASE

OPERATIONS

MAIN DEVELOPMENT PHASE

ADDITIONAL LIFE POSSIBLELAUNCH/READY FOR LAUNCH

STORAGE

MASER-11MAXUS-7/TEXUS-43TEXUS-46

Programmes

in ProgressStatus end-June 2007

BPb131.qxd 8/1/07 5:10 PM Page 50

esa bulletin 131 - august 2007www.esa.int 53

In ProgressProgrammes

52 esa bulletin 131 - august 2007 www.esa.int

Ulysses

Ulysses completed its third passage over the

Sun’s south polar cap at the beginning of

April and is now executing the rapid transit

from south to north that will bring it over the

northern polar cap at the end of the year. The

subsystems and science instruments are in

good health. The fact that Ulysses is now

coming closer to the Sun means that the

large onboard heaters are no longer needed

and there is sufficient power to operate the

full science payload without time-sharing.

As predicted, nutation returned in mid-

February, and will last for about 12 months.

During this period, the motion of the

spinning spacecraft is disturbed by non-

symmetric heating of the axial boom. The

special operational measures developed

during previous nutation episodes are being

successfully employed to keep the

disturbance under control.

On the science front, particular attention is

being paid to the changes in the cosmic

radiation detected by the instruments. The

intensity of positively charged cosmic-ray

particles measured by Ulysses during its

slow climb to high southern latitudes showed

little or no dependence on solar latitude.

Current models predict that data from the

‘fast latitude scan’ (the rapid south-to-north

transit) should show an increase in both the

galactic and anomalous cosmic ray

components as Ulysses approaches the

ecliptic. The most recent observations have

yet to reveal a clear pattern, however.

Cassini-Huygens

Cassini-Huygens held its 42nd Project

Science Group meeting in Athens, Greece, on

4–8 June. Several press and media activities

were included. A series of Huygens science

results under publication in Planetary and

Space Sciences was summarised in several

web articles on ESA’s web page in early June.

A 2-year Cassini mission extension (mid-

2008 to mid-2010) is under consideration by

NASA.

XMM-Newton

XMM-Newton is finding new ways of

investigating exploding stars. The image

below shows an XMM-Newton X-ray image

of the central regions of the Andromeda

galaxy, or M31. XMM-Newton monitored

M31 frequently for several months looking

for new X-ray emission at the positions of

known optical novae. The positions of ten

X-ray counterparts are shown as circles.

Novae occur when material builds up on the

surface of a white dwarf star and reaches

sufficient density for nuclear burning. The

resulting explosion creates a nova visible in

the optical waveband for a few to a hundred

days. The X-ray emission becomes visible

some time after the explosion, when the

matter ejected by the nova has thinned out.

This allows astronomers to peer down onto

the surface of a white dwarf that is

undergoing nuclear burning, which continues

until the fuel is exhausted.

The physics of these outbursts is still poorly

understood and the well-constrained X-ray

turn-on and turn-off times provided by XMM-

Newton are important constraints for

computer models of these explosions.

In addition, the frequent X-ray observations

have revealed a new class of novae: ones

that start to emit X-rays and then turn off

within just a few months. Such novae would

have been overlooked in previous surveys,

which looked only once every 6 months or

so. Within that time, the fast novae would

have blinked on and off.

Cluster

The four satellites and instruments are

operating nominally and the short eclipse

season was successfully passed. This year,

the eclipse period lasted 1.5 months, with a

total of 50 eclipses. Battery cycling rested

some batteries in the middle of the eclipse

season. In June–July 2007, the constellation

changed the formation of the 10 000 km

triangle formed by C1, C2 and C3 to move C3

to within 17 km of C4, the closest approach

ever by two Cluster satellites.

JSOC and ESOC operations continue to

follow the Master Science Plan. The data

return from January 2007 to end-May 2007

averaged 99.6%.

The Cluster Active Archive is operating

nominally. User access is growing every

month; 453 users (a 30% increase from

December 2006) were registered at the end

instruments instead of seven and VILSPA-2

will not be needed for the smaller volume of

data.

As of early June 2007, 614 papers had been

published in the refereed literature and 35

PhDs obtained using Cluster and Double star

data. A recent paper published by Sergeev

and co-workers showed a case study where

magnetic reconnection was observed much

closer to Earth than usual over the nightside

(< 14 Earth radii or 90 000 km). The paper

used data from TC-2, Cluster, IMAGE, GOES,

LANL and DMSP-F15.

Integral

Integral has discovered radioactive iron-60 in

the interstellar space of our Galaxy. All past

reported sightings have been subject to

controversy, but now Integral has provided

unequivocal evidence by clearly detecting the

gamma-ray emission lines that are emitted

when iron-60 decays into cobalt-60.

With the exception of the hydrogen and

helium produced in the Big Bang, the

majority of the chemical elements were built

inside stars. Previously, astronomers had

only one radioactive isotope, aluminium-26,

to probe the build-up of chemical elements

and their distribution in interstellar space.

Indeed, Integral has produced detailed maps

of the distribution of aluminium-26

throughout our Galaxy. Iron-60 is produced

deeper in stars by a different process and

expelled into space only when the star

explodes at the end of its life. By accurately

measuring the amounts of aluminium-26 and

iron-60 in our Galaxy, astronomers will be

better able to understand the processes by

which the elements are produced and how

they are distributed into interstellar space,

ready to condense to form the next

generation of stars.

Mars Express

Mars Express continues to perform its

routine operations. The Science Team met at

ESTEC 2–3 July.

The 2007 eclipse season started on 8 June

and will last until the end of August, with the

longest eclipses taking place at the end of

June. The power situation is accurately

modelled during the planning process, and in

the current eclipse season the prime science

goals (OMEGA/HRSC) are not affected by the

power available. However, MARSIS, PFS and

ASPERA science operations have had to be

reduced during parts of the eclipse season.

A substantial effort, including orbit trim

manoeuvres, is being made on the

preparations for supporting the entry-

of May 2007. After some high downloading

peaks in December and January (total

downloading rate was about 1 TB), the rate

has returned to a regular level of 30 GB per

month. CAA will produce extensive sets of

pre-generated plots (1-h, 6-h, 24-h, orbital

plots from all spacecraft) that illustrate the

various data products. This work is

approaching completion and the system is

expected to become available in summer

2007. The 2nd Operations Review, held on

15–16 May, was successful. Although there

is still a lot of work to do before the end of

the year (delivery of all data up to 2005), the

Board acknowledged the considerable work

that was accomplished in one year.

As of early June 2007, 614 papers had been

published in the refereed literature and 35

PhDs obtained using Cluster and Double Star

data. A. Retino, from IRF Uppsala, published

a paper in Nature Physics using Cluster data

showing, for the first time, magnetic

reconnection taking place in turbulent

plasma.

Double Star

The two satellites and their instruments are

operating nominally. The European Payload

Operation System, which coordinates the

operations for the seven European

instruments, is running smoothly. Data are

acquired using the VILSPA-2 ground station

in Spain and the Beijing and Shanghai

stations in China.

In October 2007, TC-1 will enter Earth’s

atmosphere. The Chinese have confirmed the

intention to continue operations of TC-2. For

ESA, operating only TC-2 will be much

simpler because it involves only two

The Deuteronilus Mensae region on Mars, an area primarilycharacterised by glacial features, was imaged on 14 March 2005by the High Resolution Stereo Camera of Mars Express.Resolution is about 29 m/pixel. (ESA/DLR/FU Berlin,G. Neukum)

An XMM-Newton EPIC imageof the central region of M31taken between 2000 and2004. (W. Pietsch, MPEGarching)

BPb131.qxd 8/1/07 5:11 PM Page 52

esa bulletin 131 - august 2007www.esa.int 53

In ProgressProgrammes

52 esa bulletin 131 - august 2007 www.esa.int

Ulysses

Ulysses completed its third passage over the

Sun’s south polar cap at the beginning of

April and is now executing the rapid transit

from south to north that will bring it over the

northern polar cap at the end of the year. The

subsystems and science instruments are in

good health. The fact that Ulysses is now

coming closer to the Sun means that the

large onboard heaters are no longer needed

and there is sufficient power to operate the

full science payload without time-sharing.

As predicted, nutation returned in mid-

February, and will last for about 12 months.

During this period, the motion of the

spinning spacecraft is disturbed by non-

symmetric heating of the axial boom. The

special operational measures developed

during previous nutation episodes are being

successfully employed to keep the

disturbance under control.

On the science front, particular attention is

being paid to the changes in the cosmic

radiation detected by the instruments. The

intensity of positively charged cosmic-ray

particles measured by Ulysses during its

slow climb to high southern latitudes showed

little or no dependence on solar latitude.

Current models predict that data from the

‘fast latitude scan’ (the rapid south-to-north

transit) should show an increase in both the

galactic and anomalous cosmic ray

components as Ulysses approaches the

ecliptic. The most recent observations have

yet to reveal a clear pattern, however.

Cassini-Huygens

Cassini-Huygens held its 42nd Project

Science Group meeting in Athens, Greece, on

4–8 June. Several press and media activities

were included. A series of Huygens science

results under publication in Planetary and

Space Sciences was summarised in several

web articles on ESA’s web page in early June.

A 2-year Cassini mission extension (mid-

2008 to mid-2010) is under consideration by

NASA.

XMM-Newton

XMM-Newton is finding new ways of

investigating exploding stars. The image

below shows an XMM-Newton X-ray image

of the central regions of the Andromeda

galaxy, or M31. XMM-Newton monitored

M31 frequently for several months looking

for new X-ray emission at the positions of

known optical novae. The positions of ten

X-ray counterparts are shown as circles.

Novae occur when material builds up on the

surface of a white dwarf star and reaches

sufficient density for nuclear burning. The

resulting explosion creates a nova visible in

the optical waveband for a few to a hundred

days. The X-ray emission becomes visible

some time after the explosion, when the

matter ejected by the nova has thinned out.

This allows astronomers to peer down onto

the surface of a white dwarf that is

undergoing nuclear burning, which continues

until the fuel is exhausted.

The physics of these outbursts is still poorly

understood and the well-constrained X-ray

turn-on and turn-off times provided by XMM-

Newton are important constraints for

computer models of these explosions.

In addition, the frequent X-ray observations

have revealed a new class of novae: ones

that start to emit X-rays and then turn off

within just a few months. Such novae would

have been overlooked in previous surveys,

which looked only once every 6 months or

so. Within that time, the fast novae would

have blinked on and off.

Cluster

The four satellites and instruments are

operating nominally and the short eclipse

season was successfully passed. This year,

the eclipse period lasted 1.5 months, with a

total of 50 eclipses. Battery cycling rested

some batteries in the middle of the eclipse

season. In June–July 2007, the constellation

changed the formation of the 10 000 km

triangle formed by C1, C2 and C3 to move C3

to within 17 km of C4, the closest approach

ever by two Cluster satellites.

JSOC and ESOC operations continue to

follow the Master Science Plan. The data

return from January 2007 to end-May 2007

averaged 99.6%.

The Cluster Active Archive is operating

nominally. User access is growing every

month; 453 users (a 30% increase from

December 2006) were registered at the end

instruments instead of seven and VILSPA-2

will not be needed for the smaller volume of

data.

As of early June 2007, 614 papers had been

published in the refereed literature and 35

PhDs obtained using Cluster and Double star

data. A recent paper published by Sergeev

and co-workers showed a case study where

magnetic reconnection was observed much

closer to Earth than usual over the nightside

(< 14 Earth radii or 90 000 km). The paper

used data from TC-2, Cluster, IMAGE, GOES,

LANL and DMSP-F15.

Integral

Integral has discovered radioactive iron-60 in

the interstellar space of our Galaxy. All past

reported sightings have been subject to

controversy, but now Integral has provided

unequivocal evidence by clearly detecting the

gamma-ray emission lines that are emitted

when iron-60 decays into cobalt-60.

With the exception of the hydrogen and

helium produced in the Big Bang, the

majority of the chemical elements were built

inside stars. Previously, astronomers had

only one radioactive isotope, aluminium-26,

to probe the build-up of chemical elements

and their distribution in interstellar space.

Indeed, Integral has produced detailed maps

of the distribution of aluminium-26

throughout our Galaxy. Iron-60 is produced

deeper in stars by a different process and

expelled into space only when the star

explodes at the end of its life. By accurately

measuring the amounts of aluminium-26 and

iron-60 in our Galaxy, astronomers will be

better able to understand the processes by

which the elements are produced and how

they are distributed into interstellar space,

ready to condense to form the next

generation of stars.

Mars Express

Mars Express continues to perform its

routine operations. The Science Team met at

ESTEC 2–3 July.

The 2007 eclipse season started on 8 June

and will last until the end of August, with the

longest eclipses taking place at the end of

June. The power situation is accurately

modelled during the planning process, and in

the current eclipse season the prime science

goals (OMEGA/HRSC) are not affected by the

power available. However, MARSIS, PFS and

ASPERA science operations have had to be

reduced during parts of the eclipse season.

A substantial effort, including orbit trim

manoeuvres, is being made on the

preparations for supporting the entry-

of May 2007. After some high downloading

peaks in December and January (total

downloading rate was about 1 TB), the rate

has returned to a regular level of 30 GB per

month. CAA will produce extensive sets of

pre-generated plots (1-h, 6-h, 24-h, orbital

plots from all spacecraft) that illustrate the

various data products. This work is

approaching completion and the system is

expected to become available in summer

2007. The 2nd Operations Review, held on

15–16 May, was successful. Although there

is still a lot of work to do before the end of

the year (delivery of all data up to 2005), the

Board acknowledged the considerable work

that was accomplished in one year.

As of early June 2007, 614 papers had been

published in the refereed literature and 35

PhDs obtained using Cluster and Double Star

data. A. Retino, from IRF Uppsala, published

a paper in Nature Physics using Cluster data

showing, for the first time, magnetic

reconnection taking place in turbulent

plasma.

Double Star

The two satellites and their instruments are

operating nominally. The European Payload

Operation System, which coordinates the

operations for the seven European

instruments, is running smoothly. Data are

acquired using the VILSPA-2 ground station

in Spain and the Beijing and Shanghai

stations in China.

In October 2007, TC-1 will enter Earth’s

atmosphere. The Chinese have confirmed the

intention to continue operations of TC-2. For

ESA, operating only TC-2 will be much

simpler because it involves only two

The Deuteronilus Mensae region on Mars, an area primarilycharacterised by glacial features, was imaged on 14 March 2005by the High Resolution Stereo Camera of Mars Express.Resolution is about 29 m/pixel. (ESA/DLR/FU Berlin,G. Neukum)

An XMM-Newton EPIC imageof the central region of M31taken between 2000 and2004. (W. Pietsch, MPEGarching)

BPb131.qxd 8/1/07 5:11 PM Page 52

esa bulletin 131 - august 2007www.esa.int 55

In ProgressProgrammes

54 esa bulletin 131 - august 2007 www.esa.int

A special section on Venus Express results

(some nine papers) will be published in

Nature after the summer. This will be

accompanied by a press conference.

The Venus Express Science Team met in

Rome 7–9 July.

A series of high temporal, spatial and

spectral resolution sequences of data was

acquired by Virtis during five consecutive

days in April. The data turned out to be

scientifically valuable and very useful as

outreach material. It is planned to repeat this

type of observation in future.

A final attempt to open the PFS scanner is

planned for early July. This will be carried out

during reaction wheel off-loading in the hope

that the vibrations may help to overcome the

initial friction.

During Vera bistatic radar operations with the

Deep Space Network, the spacecraft S-band

signal was lower than expected. This was

confirmed during later measurements

performed by New Norcia, Australia, and a

significant (about –15 dB) reduction in power

was detected. The situation is being

investigated.

A major spacecraft activity was the 180º

rotation around the z-axis to keep the solar

illumination in line with thermal constraints.

This was successful on 1 June.

Akari (Astro-F)

Akari continues operations in a healthy state.

More than 90% of the sky has been observed

twice in the survey mode. The first results

will be published as a special issue of

Publications of the Astronomical Society of

Japan, this autumn.

ESA’s contributions to the mission are

working well: the ground station coverage

from Kiruna (S) continues at a very efficient

level. More than 300 European pointed

observations were successful by the end of

June. The User Support team at ESAC

updated the user documentation with a more

thorough coverage of the processing pipeline

caveats, further to the testing performed in

spring and confirmation by the Japanese

teams. A workshop is planned at ESAC for

18–19 September to aid the European Open

Time holders in the analysis of their data.

The attitude reconstruction software,

developed at ESAC, has been further

upgraded with a distortion correction. Mass

processing of the whole mission has started,

but awaits consistently processed data from

JAXA for last year’s operations.

COROT

COROT (COnvection, ROtation and planetary

Transit) was launched into a near-perfect

orbit on 27 December 2006 and passed its

verification phase up to 2 April 2007 without

incident. Indeed, this process went so well

that scientific operations could begin on

2 February.

Under the management of CNES and in a

major partnership with ESA, Austria,

Belgium, Brazil, Germany and Spain, COROT

is the first satellite dedicated to the search

for, and the study of, planets orbiting other

stars. It is designed to detect planets as

small as our own Earth for the very first

time. A second major objective is the study

of acoustic waves in stars.

All scientific specifications have been verified

or surpassed, and the exploitation phase

(nominally 2.5 years) is now running.

Herschel/Planck

The final round of testing on the spacecraft

Flight Models is starting, following

completion of their integrations. The

Herschel cryostat is open after return from

the final qualification testing in ESTEC. It is in

Astrium ready for the integration of the

scientific instrument focal plane units. The

Herschel SPIRE instrument was the first to

be delivered and is already integrated on the

optical bench. The two other instruments will

follow in July with the final stages of their

calibration testing completed. The Herschel

Service Module activities progress well, with

the debugging and preparation for the

satellite testing later this year.

The activities on the Planck spacecraft

continue in line with the Flight Model plan.

The spacecraft is now fully assembled, with

the focal plane units (HFI and LFI) and

telescope mounted on top of the Service

Module. Major work is being carried out in

preparation for the electrical and functional

testing later this year.

Good progress is also being made on the

ground segment, with the completion of the

science ground segment implementation

reviews on both spacecraft.

LISA Pathfinder

The challenging development of

SMART-2/LISA is proceeding largely

according to schedule. The main activity in

the reporting period was the finalisation and

consolidation of the satellite design, in

preparation for the CDR. In parallel, some

subsystems have had their CDRs: the

Propulsion Module and the On Board

Computer. The Flight Models of a few

subsystems have been delivered, such as the

Science Module primary structure, the Digital

Sun Sensors and the separation system.

Some other units have been manufactured

(gyro package, low- and medium-gain

antennas) and are ready for acceptance

testing.

The two European micropropulsion

technologies (needle indium thrusters and slit

caesium thrusters) continue their challenging

development to prove the readiness of the

technologies. Many problems have been

solved and progress has been made in both

technologies. The technology suited to the

need will be selected at the beginning of

2008.

For the LISA Technology Package, many

subsystem CDRs have taken place and good

progress is being made. Many electrical units

have been built and delivered to Astrium

GmbH for the Real Time Test Bench. The

most critical subsystems are still the inertial

sensor vacuum enclosure, the electrostatic

suspension front-end electronics and the

caging mechanism. Progress has been made

on all these subsystems, but they remain

critical in terms of performance and

schedule.

The launch is expected to take place in the

first quarter of 2010.

Microscope

CNES began the Phase-C/D contract with

ONERA for the development of the T-SAGE

accelerometer. A CNES internal key-point

review is planned for December 2007 to

decide (in agreement with ESA) if the

descent-landing phase of the NASA Phoenix

mission, expected to land on Mars at either

the end of May or early June 2008.

A highly successful Mars Express data

workshop was held at ESAC 11–15 June.

This new initiative was welcomed by the

community. The first workshop focused on

(co-)analysing HRSC and OMEGA data. More

workshops on different topics will follow.

Preparation for the European Mars Science

and Exploration conference (ESTEC,

12–16 November 2007) is under way.

Rosetta

Rosetta continues its long cruise and is now

on its way to its next Earth gravity-assist on

13 November 2007. After the successful

Mars flyby earlier this year, the third Deep

Space Manoeuvre on 26 April set it precisely

on course for Earth.

On 9 May the joint Jupiter Observation

Campaign of Rosetta’s ALICE instrument and

its twin instrument on NASA’s New Horizon

spacecraft was successfully completed.

Shortly after, Passive Payload Checkout 5

was successful and the spacecraft was

prepared for near-Sun hibernation. After a

successful test on 4 June, Rosetta entered

hibernation on 5 June.

A science workshop is scheduled for

22–24 October in Athens to prepare for the

flyby of asteroid 2867 Steins on 5 September

2008.

Venus Express

Venus Express continues to perform its

routine operations. Several articles on the

observations by ESA’s Venus Express and

NASA’s Messenger spacecraft, performing a

Venus flyby on its way to Mercury, were

published at www.esa.int. One story

describes the extensive ground campaign to

observe Venus in order to place the

spacecraft observations in a broader context.

Left: integration of the Planck telescope on the spacecraft’s cryo-structure

Right: Herschel optical bench on top of the helium tank, with theSPIRE focal plane unit integrated

The LISA Pathfinder Separation System Device joins the spacecraftto the Propulsion Module. It provides the electrical connectors andthe spring system to separate the modules. The Flight Model(shown here) was manufactured by SAAB Ercicsson Space AB anddelivered to the prime contractor Astrium Ltd (UK)

BPb131.qxd 8/1/07 5:11 PM Page 54

esa bulletin 131 - august 2007www.esa.int 55

In ProgressProgrammes

54 esa bulletin 131 - august 2007 www.esa.int

A special section on Venus Express results

(some nine papers) will be published in

Nature after the summer. This will be

accompanied by a press conference.

The Venus Express Science Team met in

Rome 7–9 July.

A series of high temporal, spatial and

spectral resolution sequences of data was

acquired by Virtis during five consecutive

days in April. The data turned out to be

scientifically valuable and very useful as

outreach material. It is planned to repeat this

type of observation in future.

A final attempt to open the PFS scanner is

planned for early July. This will be carried out

during reaction wheel off-loading in the hope

that the vibrations may help to overcome the

initial friction.

During Vera bistatic radar operations with the

Deep Space Network, the spacecraft S-band

signal was lower than expected. This was

confirmed during later measurements

performed by New Norcia, Australia, and a

significant (about –15 dB) reduction in power

was detected. The situation is being

investigated.

A major spacecraft activity was the 180º

rotation around the z-axis to keep the solar

illumination in line with thermal constraints.

This was successful on 1 June.

Akari (Astro-F)

Akari continues operations in a healthy state.

More than 90% of the sky has been observed

twice in the survey mode. The first results

will be published as a special issue of

Publications of the Astronomical Society of

Japan, this autumn.

ESA’s contributions to the mission are

working well: the ground station coverage

from Kiruna (S) continues at a very efficient

level. More than 300 European pointed

observations were successful by the end of

June. The User Support team at ESAC

updated the user documentation with a more

thorough coverage of the processing pipeline

caveats, further to the testing performed in

spring and confirmation by the Japanese

teams. A workshop is planned at ESAC for

18–19 September to aid the European Open

Time holders in the analysis of their data.

The attitude reconstruction software,

developed at ESAC, has been further

upgraded with a distortion correction. Mass

processing of the whole mission has started,

but awaits consistently processed data from

JAXA for last year’s operations.

COROT

COROT (COnvection, ROtation and planetary

Transit) was launched into a near-perfect

orbit on 27 December 2006 and passed its

verification phase up to 2 April 2007 without

incident. Indeed, this process went so well

that scientific operations could begin on

2 February.

Under the management of CNES and in a

major partnership with ESA, Austria,

Belgium, Brazil, Germany and Spain, COROT

is the first satellite dedicated to the search

for, and the study of, planets orbiting other

stars. It is designed to detect planets as

small as our own Earth for the very first

time. A second major objective is the study

of acoustic waves in stars.

All scientific specifications have been verified

or surpassed, and the exploitation phase

(nominally 2.5 years) is now running.

Herschel/Planck

The final round of testing on the spacecraft

Flight Models is starting, following

completion of their integrations. The

Herschel cryostat is open after return from

the final qualification testing in ESTEC. It is in

Astrium ready for the integration of the

scientific instrument focal plane units. The

Herschel SPIRE instrument was the first to

be delivered and is already integrated on the

optical bench. The two other instruments will

follow in July with the final stages of their

calibration testing completed. The Herschel

Service Module activities progress well, with

the debugging and preparation for the

satellite testing later this year.

The activities on the Planck spacecraft

continue in line with the Flight Model plan.

The spacecraft is now fully assembled, with

the focal plane units (HFI and LFI) and

telescope mounted on top of the Service

Module. Major work is being carried out in

preparation for the electrical and functional

testing later this year.

Good progress is also being made on the

ground segment, with the completion of the

science ground segment implementation

reviews on both spacecraft.

LISA Pathfinder

The challenging development of

SMART-2/LISA is proceeding largely

according to schedule. The main activity in

the reporting period was the finalisation and

consolidation of the satellite design, in

preparation for the CDR. In parallel, some

subsystems have had their CDRs: the

Propulsion Module and the On Board

Computer. The Flight Models of a few

subsystems have been delivered, such as the

Science Module primary structure, the Digital

Sun Sensors and the separation system.

Some other units have been manufactured

(gyro package, low- and medium-gain

antennas) and are ready for acceptance

testing.

The two European micropropulsion

technologies (needle indium thrusters and slit

caesium thrusters) continue their challenging

development to prove the readiness of the

technologies. Many problems have been

solved and progress has been made in both

technologies. The technology suited to the

need will be selected at the beginning of

2008.

For the LISA Technology Package, many

subsystem CDRs have taken place and good

progress is being made. Many electrical units

have been built and delivered to Astrium

GmbH for the Real Time Test Bench. The

most critical subsystems are still the inertial

sensor vacuum enclosure, the electrostatic

suspension front-end electronics and the

caging mechanism. Progress has been made

on all these subsystems, but they remain

critical in terms of performance and

schedule.

The launch is expected to take place in the

first quarter of 2010.

Microscope

CNES began the Phase-C/D contract with

ONERA for the development of the T-SAGE

accelerometer. A CNES internal key-point

review is planned for December 2007 to

decide (in agreement with ESA) if the

descent-landing phase of the NASA Phoenix

mission, expected to land on Mars at either

the end of May or early June 2008.

A highly successful Mars Express data

workshop was held at ESAC 11–15 June.

This new initiative was welcomed by the

community. The first workshop focused on

(co-)analysing HRSC and OMEGA data. More

workshops on different topics will follow.

Preparation for the European Mars Science

and Exploration conference (ESTEC,

12–16 November 2007) is under way.

Rosetta

Rosetta continues its long cruise and is now

on its way to its next Earth gravity-assist on

13 November 2007. After the successful

Mars flyby earlier this year, the third Deep

Space Manoeuvre on 26 April set it precisely

on course for Earth.

On 9 May the joint Jupiter Observation

Campaign of Rosetta’s ALICE instrument and

its twin instrument on NASA’s New Horizon

spacecraft was successfully completed.

Shortly after, Passive Payload Checkout 5

was successful and the spacecraft was

prepared for near-Sun hibernation. After a

successful test on 4 June, Rosetta entered

hibernation on 5 June.

A science workshop is scheduled for

22–24 October in Athens to prepare for the

flyby of asteroid 2867 Steins on 5 September

2008.

Venus Express

Venus Express continues to perform its

routine operations. Several articles on the

observations by ESA’s Venus Express and

NASA’s Messenger spacecraft, performing a

Venus flyby on its way to Mercury, were

published at www.esa.int. One story

describes the extensive ground campaign to

observe Venus in order to place the

spacecraft observations in a broader context.

Left: integration of the Planck telescope on the spacecraft’s cryo-structure

Right: Herschel optical bench on top of the helium tank, with theSPIRE focal plane unit integrated

The LISA Pathfinder Separation System Device joins the spacecraftto the Propulsion Module. It provides the electrical connectors andthe spring system to separate the modules. The Flight Model(shown here) was manufactured by SAAB Ercicsson Space AB anddelivered to the prime contractor Astrium Ltd (UK)

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The JWST Partners Workshop (programme-

level meeting) was hosted by the MIRI

European Consortium in Dublin in mid-June.

More than 200 participants representing the

various parties involved in the JWST

partnership took part. The full-scale JWST

mock-up was on display during the meeting,

attracting press interest.

The vibration test of NIRSpec’s critical silicon

carbide FORE optics was successfully

completed. The FORE is NIRSpec’s largest

SiC subassembly – more than 1 m long. The

FORE mirror polishing is nearing completion.

Ion beam figuring was successful in

accelerating the convergence of the mirror

figure.

The NIRSpec Intermediate System Review

will be held in early July and will focus on a

CDR-level verification of the design by

analyses. This review will bridge the 2-year

gap between the PDR and CDR.

All European Consortium hardware for the

Optical Module of the MIRI Verification

Model has been delivered to the Rutherford

Appleton Laboratory (UK). The core

assembly of deck, spectrometer, input optics

and calibration module, and imager is

complete. Several MIRI Flight Model units

have completed their Manufacturing

Readiness Reviews (MRRs). The MRRs of

other units will follow throughout the

summer until mid-October. The first flight-

quality detector chips have been

manufactured and successfully tested by

Raytheon.

The planning for the PDR analysis campaign

(RAMP) has been finalised and will constitute

an input to the JWST mission-level PDR in

March 2008.

BepiColombo

The critical actions identified by the

spacecraft System Requirements Review

have been completed and the close-out

report written. The system, support and

subsystem specifications have been

consolidated and the equipment procurement

phase is under way.

A number of activities have begun to advance

key technologies before the start of

equipment procurement. This involves work

on multi-layer insulation, radiator, blocking

diodes, solar array, high-temperature rotary

joint and high-gain antenna. Both candidate

electrical propulsion engines have

successfully completed 5500 h of tests. The

lifetime predictions are exceeding the project

requirement. Work has started to upgrade

the Large Space Simulator at ESTEC to

10 solar constants.

The System Requirements Review for all 11

instruments of the Mercury Planetary Orbiter

has been conducted. The scientific

performances were confirmed and the design

definition is generally adequate. However,

further work was requested for four

instruments before close-out of the review, in

particular to consolidate the thermal design.

The overall payload mass could be brought

back to within the allocation with some

margin.

Work at JAXA on the Mercury

Magnetospheric Orbiter design is

progressing nominally and is being finalised

in preparation for the PDR at end-2007. The

mass of the spacecraft could be reduced by

10 kg, which almost satisfies the allocation.

GOCE

The Gradiometer Core proto-flight model

(PFM) passed its mechanical and thermal

vacuum acceptance testing, respectively, in

May and June. Satellite PFM integration and

testing activities continued, in double shifts,

at Thales Alenia Space in Turin (I). A satellite

Integrated System Test, covering the launch

and early orbit phase, and a System

Validation Test involving ESOC were

successful. The Ion Propulsion Assembly

completed its final acceptance testing in

QinetiQ (UK) and arrived in Turin at the end

of June ready to be integrated on the

satellite.

Good progress has also been made on the

launch vehicle; the Qualification Review with

Eurockot was completed at the end of April.

The GOCE Ground Segment Overall

Validation activities are close to completion,

with tests performed between the Flight

Operations Segment and the Payload Data

Ground Segment. Work on the Calibration

and Monitoring Facility and the High Level

Processing Facility of the European GOCE

Gravity Consortium has progressed as

planned.

CryoSat-2

Mechanical preparation of the satellite is

complete, with the installation of pipework

for the thruster subsystem and other

hardware such as brackets and fittings. The

bare solar array panels were installed and

alignment pins fitted before the panels were

shipped to Emcore in Albuquerque (US),

where the advanced solar cells and

associated electrical hardware will be

installed. Several equipment units were

delivered and more are expected in the near

future; integration of the satellite is starting.

The main payload, the redundant SIRAL

radar altimeter, is also coming together. Most

of the individual units are now delivered and

tuning of the transmitters is well advanced.

The antenna reflectors were found to have a

manufacturing defect, so they were scrapped

and replacements are being built. This work

has been absorbed with no impact on the

overall schedule.

The Ground Segment PDR was held during

May 2007, covering both the Flight

Operations Segment and the Payload Data

Ground Segment. This review scrutinised the

documents defining all of the requirements

on the various facilities that constitute the

ground segment, as well as higher level

overall documentation. The documents were

finalised by taking the review findings into

account, and the various sets of contractual

documents were prepared.

SMOS

After completion of the thermal balance/

thermal vacuum testing in ESTEC’s Large

Space Simulator, the payload was transferred

to the Maxwell facility, which is a large

chamber carefully shielded from all

electromagnetic radiation. Two distinct

measurement campaigns were conducted

Microscope drag-free propulsion remains

FEEP or if it should switch to cold gas. This

decision is pending the results of the LISA

Pathfinder micropropulsion development

activities.

Gaia

All flight hardware suppliers have been

competitively selected; a few procurements

for support tasks and test equipment are still

open. Around 80 procurements have been

handled according to ESA’s ‘best practice’,

most of them competitively, while a very

small number were performed in direct

negotiations.

The workload during this reporting period

focused on the preparation and execution of

the PDR. About 40 project-independent

engineers, predominantly from the Technical

Directorate, reviewed the data package

delivered by the Prime Contractor. The final

step was the meeting of the Review Board on

29 June.

Meetings of the Gaia Science Teams and

related working groups have taken place. The

Science Team and the Radiation Calibration

Working Group were briefed about the latest

radiation test results on flight-representative

CCDs. Both groups expressed their

satisfaction about the results and agreed on

a way-forward strategy to be developed

through the Radiation Work Plan.

ESA’s science advisory structure endorsed

both the new composition of the Gaia

Science Team and the formation of the Data

Processing Analysis Consortium. Both

endorsements conclude competitive

selections following an Announcement of

Opportunity.

JWST

The Director General and the NASA

Administrator, Michael Griffin, signed the

JWST Memorandum of Understanding at a

ceremony on 18 June at the Paris Air Show.

Qualification Model of JWST’s NIRSpec FORE three-mirroranastigmat

BepiColomboPlanetary and

MagnetosphericOrbiters

Electromagnetic testing of the SMOS payload at ESTEC

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In ProgressProgrammes

56 esa bulletin 131 - august 2007 www.esa.int

The JWST Partners Workshop (programme-

level meeting) was hosted by the MIRI

European Consortium in Dublin in mid-June.

More than 200 participants representing the

various parties involved in the JWST

partnership took part. The full-scale JWST

mock-up was on display during the meeting,

attracting press interest.

The vibration test of NIRSpec’s critical silicon

carbide FORE optics was successfully

completed. The FORE is NIRSpec’s largest

SiC subassembly – more than 1 m long. The

FORE mirror polishing is nearing completion.

Ion beam figuring was successful in

accelerating the convergence of the mirror

figure.

The NIRSpec Intermediate System Review

will be held in early July and will focus on a

CDR-level verification of the design by

analyses. This review will bridge the 2-year

gap between the PDR and CDR.

All European Consortium hardware for the

Optical Module of the MIRI Verification

Model has been delivered to the Rutherford

Appleton Laboratory (UK). The core

assembly of deck, spectrometer, input optics

and calibration module, and imager is

complete. Several MIRI Flight Model units

have completed their Manufacturing

Readiness Reviews (MRRs). The MRRs of

other units will follow throughout the

summer until mid-October. The first flight-

quality detector chips have been

manufactured and successfully tested by

Raytheon.

The planning for the PDR analysis campaign

(RAMP) has been finalised and will constitute

an input to the JWST mission-level PDR in

March 2008.

BepiColombo

The critical actions identified by the

spacecraft System Requirements Review

have been completed and the close-out

report written. The system, support and

subsystem specifications have been

consolidated and the equipment procurement

phase is under way.

A number of activities have begun to advance

key technologies before the start of

equipment procurement. This involves work

on multi-layer insulation, radiator, blocking

diodes, solar array, high-temperature rotary

joint and high-gain antenna. Both candidate

electrical propulsion engines have

successfully completed 5500 h of tests. The

lifetime predictions are exceeding the project

requirement. Work has started to upgrade

the Large Space Simulator at ESTEC to

10 solar constants.

The System Requirements Review for all 11

instruments of the Mercury Planetary Orbiter

has been conducted. The scientific

performances were confirmed and the design

definition is generally adequate. However,

further work was requested for four

instruments before close-out of the review, in

particular to consolidate the thermal design.

The overall payload mass could be brought

back to within the allocation with some

margin.

Work at JAXA on the Mercury

Magnetospheric Orbiter design is

progressing nominally and is being finalised

in preparation for the PDR at end-2007. The

mass of the spacecraft could be reduced by

10 kg, which almost satisfies the allocation.

GOCE

The Gradiometer Core proto-flight model

(PFM) passed its mechanical and thermal

vacuum acceptance testing, respectively, in

May and June. Satellite PFM integration and

testing activities continued, in double shifts,

at Thales Alenia Space in Turin (I). A satellite

Integrated System Test, covering the launch

and early orbit phase, and a System

Validation Test involving ESOC were

successful. The Ion Propulsion Assembly

completed its final acceptance testing in

QinetiQ (UK) and arrived in Turin at the end

of June ready to be integrated on the

satellite.

Good progress has also been made on the

launch vehicle; the Qualification Review with

Eurockot was completed at the end of April.

The GOCE Ground Segment Overall

Validation activities are close to completion,

with tests performed between the Flight

Operations Segment and the Payload Data

Ground Segment. Work on the Calibration

and Monitoring Facility and the High Level

Processing Facility of the European GOCE

Gravity Consortium has progressed as

planned.

CryoSat-2

Mechanical preparation of the satellite is

complete, with the installation of pipework

for the thruster subsystem and other

hardware such as brackets and fittings. The

bare solar array panels were installed and

alignment pins fitted before the panels were

shipped to Emcore in Albuquerque (US),

where the advanced solar cells and

associated electrical hardware will be

installed. Several equipment units were

delivered and more are expected in the near

future; integration of the satellite is starting.

The main payload, the redundant SIRAL

radar altimeter, is also coming together. Most

of the individual units are now delivered and

tuning of the transmitters is well advanced.

The antenna reflectors were found to have a

manufacturing defect, so they were scrapped

and replacements are being built. This work

has been absorbed with no impact on the

overall schedule.

The Ground Segment PDR was held during

May 2007, covering both the Flight

Operations Segment and the Payload Data

Ground Segment. This review scrutinised the

documents defining all of the requirements

on the various facilities that constitute the

ground segment, as well as higher level

overall documentation. The documents were

finalised by taking the review findings into

account, and the various sets of contractual

documents were prepared.

SMOS

After completion of the thermal balance/

thermal vacuum testing in ESTEC’s Large

Space Simulator, the payload was transferred

to the Maxwell facility, which is a large

chamber carefully shielded from all

electromagnetic radiation. Two distinct

measurement campaigns were conducted

Microscope drag-free propulsion remains

FEEP or if it should switch to cold gas. This

decision is pending the results of the LISA

Pathfinder micropropulsion development

activities.

Gaia

All flight hardware suppliers have been

competitively selected; a few procurements

for support tasks and test equipment are still

open. Around 80 procurements have been

handled according to ESA’s ‘best practice’,

most of them competitively, while a very

small number were performed in direct

negotiations.

The workload during this reporting period

focused on the preparation and execution of

the PDR. About 40 project-independent

engineers, predominantly from the Technical

Directorate, reviewed the data package

delivered by the Prime Contractor. The final

step was the meeting of the Review Board on

29 June.

Meetings of the Gaia Science Teams and

related working groups have taken place. The

Science Team and the Radiation Calibration

Working Group were briefed about the latest

radiation test results on flight-representative

CCDs. Both groups expressed their

satisfaction about the results and agreed on

a way-forward strategy to be developed

through the Radiation Work Plan.

ESA’s science advisory structure endorsed

both the new composition of the Gaia

Science Team and the formation of the Data

Processing Analysis Consortium. Both

endorsements conclude competitive

selections following an Announcement of

Opportunity.

JWST

The Director General and the NASA

Administrator, Michael Griffin, signed the

JWST Memorandum of Understanding at a

ceremony on 18 June at the Paris Air Show.

Qualification Model of JWST’s NIRSpec FORE three-mirroranastigmat

BepiColomboPlanetary and

MagnetosphericOrbiters

Electromagnetic testing of the SMOS payload at ESTEC

BPb131.qxd 8/1/07 5:11 PM Page 56

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In ProgressProgrammes

58 esa bulletin 131 - august 2007 www.esa.int

Assembly of the ALADIN instrument

continues; all units with the exception of the

Mie-Spectrometer (MSP) are now integrated.

Delivery of the MSP was delayed because of

anomalies detected during unit-level

mechanical tests. The repair of this unit is

under way.

The integration and test activities of the

satellite platform at Astrium Friedrichshafen

(D) are largely completed. Shipment of the

platform to Astrium Stevenage (UK) for the

integration of the remaining platform

hardware and performance of further

platform-level tests is planned for July.

The flight campaign of the Aladin Airborne

Demonstrator (A2D) is planned for October

2007. In preparation for this milestone, the

A2D hardware was assembled by DLR at the

German Weather Service’s Lindenberg test

site for a final Aeolus ground campaign in

July.

Swarm

Progress has been made since the Satellite

PDR in conducting lower level PDRs, in

particular the satellite structure, boom

assembly and thermal subsystem. The major

elements are in progress: the engineering

models of the accelerometer, vector

magnetometer and scalar magnetometer are

being built. The development of the optical

bench that supports the vector

magnetometer and the three startrackers has

begun. Two startracker prototypes showed

excellent results on the optical test bench of

Astrium GmbH in Ottobrunn (D).

A peer review with experts from the Cluster,

Oersted and CHAMP missions was held in

Potsdam (D) to review the methodology for

the ground characterisation and in-orbit

verification of the magnetic performance of

the spacecraft, and to prepare a draft plan.

The latest meeting with Eurockot showed

significant progress, in particular in flight

dynamics and collision avoidance. There is a

solid concept of the satellite dispenser.

Subcontractors were selected for the boom,

solar cells and tanks. Specifications were

prepared for the harness, thrusters and

magnetotorquers. The level-1b algorithms for

the magnetic package and the EFI instrument

were released by industry. Work is beginning

on level-2 algorithms, with four studies

starting on processing architecture,

ionospheric current, mantle conductivity and

air density.

MetOp

MetOp-A, Europe’s first polar-orbiting

meteorological satellite was declared

operational on 15 May 2007, after only

6 months of commissioning, starting a new

era of meteorology and climatology.

The first science data were received 2 days

after the Launch and Early-Orbit Phase, but

the full data flow from the 11 instruments is

now available to users on an operational

basis, offering unprecedented accuracy and

resolution of variables such as temperature

and humidity, wind speed, ozone and

measurements of trace gases such as carbon

dioxide, nitrous oxide and methane.

MetOp data will significantly improve weather

forecasting by, for example, direct

assimilation into numerical weather

there: the electromagnetic compatibility test

demonstrated that the instrument is not

disturbed by its own or the platform’s

operations, and the image validation test in

which an artificial source mounted to the

ceiling was used to produce an image and to

exercise the sophisticated data processing.

With this campaign successfully completed,

the payload was transported to Cannes (F),

where it was mated by Thales Alenia Space

with the Proteus platform to form the

integrated satellite.

The Final Mission Analysis Meeting was

successful for the Rockot launcher, with only

one thermal analysis case still to be refined

and completed.

Step-by-step integration testing of the flight

operations ground segment with CNES has

started, while the data processing ground

segment is still integrating alpha versions of

all the facilities.

ADM-Aeolus

The first Flight Model of the modified

transmitter laser master oscillator was

assembled and IR laser operation

demonstrated. The modifications were

necessary to improve the thermo-mechanical

stability of the laser. Assembly of the mirror

assemblies for the second Flight Model of

the master oscillator is under way.

prediction models that compute forecasts

ranging from a few hours to up to 10 days

ahead.

The MetOp-A satellite shows excellent

performance. The project and industrial

activities are now in a standby mode, with

MetOp-1 (MetOp-B) and MetOp-3 (MetOp-C)

in storage, waiting for the restart in 2009 for

the next launch (MetOp-B), in 2010.

MSG

Meteosat-8/MSG-1

The satellite was hit by an object on 22 May

that raised the orbit by about 130 m. Initial

investigations revealed that the R1 thruster is

bent and that some multi-layer insulation is

damaged. The propulsion system shows no

leakage; the unaffected redundant thruster

branch became the nominal one.

Satellite performance, which is operating in

Rapid Scan mode, and instrument

performance remain of excellent quality.

Meteosat-9/MSG-2

Meteosat-9 is now Eumetsat’s nominal

operational satellite at 0º longitude.

MSG-3

It is planned to move MSG-3 from inter-

mediate storage in the Thales Alenia Space

cleanroom into a long-term storage in

autumn 2007. Launch is projected for early

2011.

MSG-4

After successful completion of its Pre-

Storage Review, MSG-4 will be prepared for

long-term storage. Launch is planned for no

earlier than 2013.

Human Spaceflight,

Microgravity &

Exploration

Highlights

The ExoMars Enhanced Baseline Mission

configuration received a preliminary

endorsement by the Participating States in a

meeting of the HME Programme Board on

11 June.

The concluded work on, and the public

release of, The Global Exploration Strategy:

The Framework for Coordination document

of 14 world space organisations was the

focus of the third ESA/ASI workshop, on

‘International Cooperation for Sustainable

Space Exploration’, held in Spineto (I) from

30 May to 1 June. The workshop was opened

by D/HME, the Administrator of the China

National Space Agency and the ASI

President. More than 70 representatives from

16 space agencies and organisations

attended, plus non-governmental entities

such as COSPAR. This group of space

organisation representatives will continue to

work on the principles that will inform the

international coordination mechanism and

the open reference architecture. These will be

the topics of a meeting to be held in

connection with the ‘International Space

Exploration Conference’ in Berlin on

8–9 November.

At the Paris Air Show in Le Bourget, the

ESA/ASI agreement for the joint management

of Paolo Nespoli, as mission member of the

STS-120 crew, was signed by the ASI

President and D/HME. Also announced by

ESA was the MARS-500 study, and a call was

made for European and Canadian candidates.

International Space Station

Space Shuttle Atlantis, STS-117, was

launched from the Kennedy Space Center

Right: the latest Swarm satellite configuration. The optical benchwith the startrackers and the vector field magnetometer sensorsare in the middle of the boom. The absolute scalar magnetometersensors are at the top of the boom. (Astrium GmbH)

Left: the SMOS payload meets its Proteus platform in Cannes; theSMOS satellite is born!

Above: the total amount of nitrogen dioxide (NO2) in theatmosphere above Europe on 4 February 2007, as measured bythe GOME-2 instrument on MetOp-A. GOME-2 can measure NO2

worldwide on a daily basis at a city-scale. (Eumetsat)

Right: severe thunderstorms developed along a low-level airmassboundary in France and Germany on 25 May 2007. In theafternoon, Paris and Berlin were hit simultaneously by majorthunderstorms. The high repeat cycle of Meteosat-8 is essentialfor the early detection of rapidly developing thunderstorms

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58 esa bulletin 131 - august 2007 www.esa.int

Assembly of the ALADIN instrument

continues; all units with the exception of the

Mie-Spectrometer (MSP) are now integrated.

Delivery of the MSP was delayed because of

anomalies detected during unit-level

mechanical tests. The repair of this unit is

under way.

The integration and test activities of the

satellite platform at Astrium Friedrichshafen

(D) are largely completed. Shipment of the

platform to Astrium Stevenage (UK) for the

integration of the remaining platform

hardware and performance of further

platform-level tests is planned for July.

The flight campaign of the Aladin Airborne

Demonstrator (A2D) is planned for October

2007. In preparation for this milestone, the

A2D hardware was assembled by DLR at the

German Weather Service’s Lindenberg test

site for a final Aeolus ground campaign in

July.

Swarm

Progress has been made since the Satellite

PDR in conducting lower level PDRs, in

particular the satellite structure, boom

assembly and thermal subsystem. The major

elements are in progress: the engineering

models of the accelerometer, vector

magnetometer and scalar magnetometer are

being built. The development of the optical

bench that supports the vector

magnetometer and the three startrackers has

begun. Two startracker prototypes showed

excellent results on the optical test bench of

Astrium GmbH in Ottobrunn (D).

A peer review with experts from the Cluster,

Oersted and CHAMP missions was held in

Potsdam (D) to review the methodology for

the ground characterisation and in-orbit

verification of the magnetic performance of

the spacecraft, and to prepare a draft plan.

The latest meeting with Eurockot showed

significant progress, in particular in flight

dynamics and collision avoidance. There is a

solid concept of the satellite dispenser.

Subcontractors were selected for the boom,

solar cells and tanks. Specifications were

prepared for the harness, thrusters and

magnetotorquers. The level-1b algorithms for

the magnetic package and the EFI instrument

were released by industry. Work is beginning

on level-2 algorithms, with four studies

starting on processing architecture,

ionospheric current, mantle conductivity and

air density.

MetOp

MetOp-A, Europe’s first polar-orbiting

meteorological satellite was declared

operational on 15 May 2007, after only

6 months of commissioning, starting a new

era of meteorology and climatology.

The first science data were received 2 days

after the Launch and Early-Orbit Phase, but

the full data flow from the 11 instruments is

now available to users on an operational

basis, offering unprecedented accuracy and

resolution of variables such as temperature

and humidity, wind speed, ozone and

measurements of trace gases such as carbon

dioxide, nitrous oxide and methane.

MetOp data will significantly improve weather

forecasting by, for example, direct

assimilation into numerical weather

there: the electromagnetic compatibility test

demonstrated that the instrument is not

disturbed by its own or the platform’s

operations, and the image validation test in

which an artificial source mounted to the

ceiling was used to produce an image and to

exercise the sophisticated data processing.

With this campaign successfully completed,

the payload was transported to Cannes (F),

where it was mated by Thales Alenia Space

with the Proteus platform to form the

integrated satellite.

The Final Mission Analysis Meeting was

successful for the Rockot launcher, with only

one thermal analysis case still to be refined

and completed.

Step-by-step integration testing of the flight

operations ground segment with CNES has

started, while the data processing ground

segment is still integrating alpha versions of

all the facilities.

ADM-Aeolus

The first Flight Model of the modified

transmitter laser master oscillator was

assembled and IR laser operation

demonstrated. The modifications were

necessary to improve the thermo-mechanical

stability of the laser. Assembly of the mirror

assemblies for the second Flight Model of

the master oscillator is under way.

prediction models that compute forecasts

ranging from a few hours to up to 10 days

ahead.

The MetOp-A satellite shows excellent

performance. The project and industrial

activities are now in a standby mode, with

MetOp-1 (MetOp-B) and MetOp-3 (MetOp-C)

in storage, waiting for the restart in 2009 for

the next launch (MetOp-B), in 2010.

MSG

Meteosat-8/MSG-1

The satellite was hit by an object on 22 May

that raised the orbit by about 130 m. Initial

investigations revealed that the R1 thruster is

bent and that some multi-layer insulation is

damaged. The propulsion system shows no

leakage; the unaffected redundant thruster

branch became the nominal one.

Satellite performance, which is operating in

Rapid Scan mode, and instrument

performance remain of excellent quality.

Meteosat-9/MSG-2

Meteosat-9 is now Eumetsat’s nominal

operational satellite at 0º longitude.

MSG-3

It is planned to move MSG-3 from inter-

mediate storage in the Thales Alenia Space

cleanroom into a long-term storage in

autumn 2007. Launch is projected for early

2011.

MSG-4

After successful completion of its Pre-

Storage Review, MSG-4 will be prepared for

long-term storage. Launch is planned for no

earlier than 2013.

Human Spaceflight,

Microgravity &

Exploration

Highlights

The ExoMars Enhanced Baseline Mission

configuration received a preliminary

endorsement by the Participating States in a

meeting of the HME Programme Board on

11 June.

The concluded work on, and the public

release of, The Global Exploration Strategy:

The Framework for Coordination document

of 14 world space organisations was the

focus of the third ESA/ASI workshop, on

‘International Cooperation for Sustainable

Space Exploration’, held in Spineto (I) from

30 May to 1 June. The workshop was opened

by D/HME, the Administrator of the China

National Space Agency and the ASI

President. More than 70 representatives from

16 space agencies and organisations

attended, plus non-governmental entities

such as COSPAR. This group of space

organisation representatives will continue to

work on the principles that will inform the

international coordination mechanism and

the open reference architecture. These will be

the topics of a meeting to be held in

connection with the ‘International Space

Exploration Conference’ in Berlin on

8–9 November.

At the Paris Air Show in Le Bourget, the

ESA/ASI agreement for the joint management

of Paolo Nespoli, as mission member of the

STS-120 crew, was signed by the ASI

President and D/HME. Also announced by

ESA was the MARS-500 study, and a call was

made for European and Canadian candidates.

International Space Station

Space Shuttle Atlantis, STS-117, was

launched from the Kennedy Space Center

Right: the latest Swarm satellite configuration. The optical benchwith the startrackers and the vector field magnetometer sensorsare in the middle of the boom. The absolute scalar magnetometersensors are at the top of the boom. (Astrium GmbH)

Left: the SMOS payload meets its Proteus platform in Cannes; theSMOS satellite is born!

Above: the total amount of nitrogen dioxide (NO2) in theatmosphere above Europe on 4 February 2007, as measured bythe GOME-2 instrument on MetOp-A. GOME-2 can measure NO2

worldwide on a daily basis at a city-scale. (Eumetsat)

Right: severe thunderstorms developed along a low-level airmassboundary in France and Germany on 25 May 2007. In theafternoon, Paris and Berlin were hit simultaneously by majorthunderstorms. The high repeat cycle of Meteosat-8 is essentialfor the early detection of rapidly developing thunderstorms

BPb131.qxd 8/1/07 5:11 PM Page 58

In ProgressProgrammes

60 esa bulletin 131 - august 2007 www.esa.int

objective of transferring the lessons-learned

to Columbus operations.

In Paris, on 28 May, the 8th meeting of the

HME Programme Board endorsed the results

of the Announcement of Opportunity (AO-06-

BR) for the Bed Rest Studies in ELIPS-2

during 2007–2009. Following the installation

of ESA’s first Short-Arm Human Centrifuge, at

MEDES, Toulouse (F), the Human Exploration

preparation benefits of bed rest activities have

been enhanced by the combination with

artificial gravity.

The Norwegian User Support and Operation

Centre (N-USOC), having commissioned the

European Modular Cultivation System (EMCS)

in the Destiny ISS module and successfully

performed NASA’s TROPI experiment, also

completed ESA’s GRAVI-1 experiment. TROPI

investigated cellular mechanisms of

phototropism and determined the effects and

influences of gravity on light perception in

plants. GRAVI-1 subjected lentil (Lens

culinaris var. anicia) seedling roots to

centrifugal acceleration to determine the

threshold acceleration at which the root

responds to the gravity stimulus.

ESA’s second EMCS experiment, Multigen-1,

is ready for flight and due to be launched in

August aboard STS-118 for installation in

EMCS.

After agreements with Space Adventures, Ltd.

and Roskosmos, Charles Simonyi, as a

visiting Soyuz cosmonaut during the docked

period in April, performed five human

physiology experiments for ESA. The first

results of the experimental package indicate a

high success rate.

During ISS Increment-15, the Russian crew is

performing several long-duration science

experiments for ESA. In addition, GTS-2 and

the radiation-measurement experiment

Matroshka-2B will begin during the

Increment.

ANITA (Analysing Interferometer for Ambient

Air) was shipped to KSC for final interface

testing with the host Express rack. Manifested

for STS-118, ANITA will provide superior ISS

cabin air analysis of more than 30 volatile

(KSC) on 8 June. The launch followed repairs

to the External Tank after a severe hailstorm

at the end of February. During four EVAs, the

crew attached the new S3/S4 solar array

Truss segment on the starboard side of the

Station’s backbone, deployed a new set of

solar arrays, and retracted the remaining P6

solar array in readiness for relocation to its

final destination later this year. The Station

has a new look, with two symmetrical

solar panels mounted on each end of the

Truss. After a 12-day mission, Atlantis

touched down safely at the secondary

landing site of Edwards Air Force Base in

California because poor weather conditions

over KSC prevented use of the primary

landing site.

Space Shuttle Endeavour, flying STS-118, is

targeted for a launch window no earlier than

7 August. It will carry the Spacehab Single

Cargo Module, the starboard Truss segment

S5 and External Stowage Platform 3.

STS-120, using Space Shuttle Discovery,

scheduled to transport Node-2 ‘Harmony’,

along with ESA astronaut Paolo Nespoli, is

targeted for launch no earlier than

16 October 2007.

61esa bulletin 131 - august 2007www.esa.int

STS-122, the mission for the transportation

of the Columbus laboratory, is now targeted

for no earlier than 6 December 2007, on

Atlantis instead of Discovery. This mission

will include ESA astronauts Hans Schlegel

and Léopold Eyharts. While Eyharts will

remain aboard the Station for up to 3 months

to oversee the activation and commissioning

of Columbus, Schlegel will return on the

Shuttle 12 days after launch.

Progress-25P was launched from Baikonur

Cosmodrome on 12 May carrying 2.5 t of

supplies: oxygen, water, food, propellant,

consumables, scientific equipment and

hardware, all necessary to maintain ISS

operations and provide for the crew. Part of

the scientific equipment aboard was GTS-2

(Global Transmission Service-2), a

technology experiment for the test, validation

and demonstration of radio transmission

techniques for the synchronisation of Earth-

based clocks and watches from the ISS. In

addition, the GTS data services, based on a

unique coding scheme, could ultimately lead

to commercial services such as the blocking

of stolen cars or lost credit cards, directly

from space.

The Space Station Control Board baselined

Shuttle, Progress, Soyuz and Automated

Transfer Vehicle (ATV) launches through to

April 2008.

Space Infrastructure Development

ATV Jules Verne integration and testing,

together with system functional qualification

tests, were successfully completed.On

28 June, members of the international media

visited the cleanrooms at ESTEC to view ATV

for the last time in Europe. They had the

chance to interview D/HME, John Ellwood

(ESA ATV Programme Manager) and Nicolas

Chamussy (Astrium ATV Programme

Director) on the programme.

The Pre-Shipment Review was held at ESA’s

premises in Les Mureaux (F) on 4 July. This

review confirmed that all the required work

had been performed on the spacecraft in

Europe, giving the green light to ship it to the

launch site in Kourou, French Guiana. The

spacecraft and all its ground support

equipment, with a total weight of 400 t, left

Rotterdam in mid-July. Once in Kourou, at

the end of July, the launch campaign testing

and integration continued. The launch

schedule was revised to allow for the ‘heavy

traffic’ to the ISS at the end of the year and

will now be no earlier than January 2008.

Meanwhile, the System Qualification Review

is well underway, with the board meeting

planned for September.

After delivery of the new version of the

Russian Service Module Simulator, the ATV

Control Centre is preparing to support the

Joint Integrated Simulations Programme now

established with NASA and Roskosmos.

Engineering support tools were exercised

during the ATV System Validation Test and

the ATV Cargo Safety Review was conducted.

Columbus spares, for launch on the first ATV,

have been identified and are being prepared

for delivery. The spares will be stowed

aboard the ISS to improve Columbus

availability and reduce future upload

transportation costs.

At KSC, the Columbus system checkout test

was followed by the final modifications and

adjustments to the payload racks, including

the final integration of the Canadian Space

Agency-developed Microgravity Vibration

Isolation System into the Fluid Science

Laboratory (FSL) of Columbus. The EuTEF

and Solar external payload packages are in

the final stages of acceptance and will be

shipped to KSC this summer. The FlyWheel

Exercise Device, GEOFLOW and WAICO

experiments, to be performed standalone and

in the Biolab and FSL racks, respectively, are

integrated in the European Transport Carrier

rack. WAICO is expected to be delivered to

KSC by September for Shuttle mid-deck

stowage.

The Columbus Control Centre (COL-CC)

development contract was completed;

COL-CC is now maintained as a part of the

ISS Operations Services Contract. The

operations qualification, training and

simulations programmes for both ATV and

Columbus are progressing on schedule.

Node-2 ‘Harmony’, having completed close-

out, is in the cleanroom at KSC with its hatch

closed waiting for integration and preparation

for launch in October. Node-3, having

completed its Element Leak Test, Engineering

Review and Preliminary Acceptance Review,

will be maintained in Europe, at the request

of NASA, until mid-2009. Once delivered to

KSC in 2009, it will undergo flight close-out

and then be integrated with Cupola (currently

stored at KSC) for launch together in late

spring 2010.

Utilisation

A debriefing of the AstroLab mission

operations was held at COL-CC, with the

participation of all the parties, with the prime

ATV begins its journey to the launch site

The configuration of the ISS as STS-117 left in June 2007

The Columbus Control Centre

BPb131.qxd 8/1/07 5:11 PM Page 60

In ProgressProgrammes

60 esa bulletin 131 - august 2007 www.esa.int

objective of transferring the lessons-learned

to Columbus operations.

In Paris, on 28 May, the 8th meeting of the

HME Programme Board endorsed the results

of the Announcement of Opportunity (AO-06-

BR) for the Bed Rest Studies in ELIPS-2

during 2007–2009. Following the installation

of ESA’s first Short-Arm Human Centrifuge, at

MEDES, Toulouse (F), the Human Exploration

preparation benefits of bed rest activities have

been enhanced by the combination with

artificial gravity.

The Norwegian User Support and Operation

Centre (N-USOC), having commissioned the

European Modular Cultivation System (EMCS)

in the Destiny ISS module and successfully

performed NASA’s TROPI experiment, also

completed ESA’s GRAVI-1 experiment. TROPI

investigated cellular mechanisms of

phototropism and determined the effects and

influences of gravity on light perception in

plants. GRAVI-1 subjected lentil (Lens

culinaris var. anicia) seedling roots to

centrifugal acceleration to determine the

threshold acceleration at which the root

responds to the gravity stimulus.

ESA’s second EMCS experiment, Multigen-1,

is ready for flight and due to be launched in

August aboard STS-118 for installation in

EMCS.

After agreements with Space Adventures, Ltd.

and Roskosmos, Charles Simonyi, as a

visiting Soyuz cosmonaut during the docked

period in April, performed five human

physiology experiments for ESA. The first

results of the experimental package indicate a

high success rate.

During ISS Increment-15, the Russian crew is

performing several long-duration science

experiments for ESA. In addition, GTS-2 and

the radiation-measurement experiment

Matroshka-2B will begin during the

Increment.

ANITA (Analysing Interferometer for Ambient

Air) was shipped to KSC for final interface

testing with the host Express rack. Manifested

for STS-118, ANITA will provide superior ISS

cabin air analysis of more than 30 volatile

(KSC) on 8 June. The launch followed repairs

to the External Tank after a severe hailstorm

at the end of February. During four EVAs, the

crew attached the new S3/S4 solar array

Truss segment on the starboard side of the

Station’s backbone, deployed a new set of

solar arrays, and retracted the remaining P6

solar array in readiness for relocation to its

final destination later this year. The Station

has a new look, with two symmetrical

solar panels mounted on each end of the

Truss. After a 12-day mission, Atlantis

touched down safely at the secondary

landing site of Edwards Air Force Base in

California because poor weather conditions

over KSC prevented use of the primary

landing site.

Space Shuttle Endeavour, flying STS-118, is

targeted for a launch window no earlier than

7 August. It will carry the Spacehab Single

Cargo Module, the starboard Truss segment

S5 and External Stowage Platform 3.

STS-120, using Space Shuttle Discovery,

scheduled to transport Node-2 ‘Harmony’,

along with ESA astronaut Paolo Nespoli, is

targeted for launch no earlier than

16 October 2007.

61esa bulletin 131 - august 2007www.esa.int

STS-122, the mission for the transportation

of the Columbus laboratory, is now targeted

for no earlier than 6 December 2007, on

Atlantis instead of Discovery. This mission

will include ESA astronauts Hans Schlegel

and Léopold Eyharts. While Eyharts will

remain aboard the Station for up to 3 months

to oversee the activation and commissioning

of Columbus, Schlegel will return on the

Shuttle 12 days after launch.

Progress-25P was launched from Baikonur

Cosmodrome on 12 May carrying 2.5 t of

supplies: oxygen, water, food, propellant,

consumables, scientific equipment and

hardware, all necessary to maintain ISS

operations and provide for the crew. Part of

the scientific equipment aboard was GTS-2

(Global Transmission Service-2), a

technology experiment for the test, validation

and demonstration of radio transmission

techniques for the synchronisation of Earth-

based clocks and watches from the ISS. In

addition, the GTS data services, based on a

unique coding scheme, could ultimately lead

to commercial services such as the blocking

of stolen cars or lost credit cards, directly

from space.

The Space Station Control Board baselined

Shuttle, Progress, Soyuz and Automated

Transfer Vehicle (ATV) launches through to

April 2008.

Space Infrastructure Development

ATV Jules Verne integration and testing,

together with system functional qualification

tests, were successfully completed.On

28 June, members of the international media

visited the cleanrooms at ESTEC to view ATV

for the last time in Europe. They had the

chance to interview D/HME, John Ellwood

(ESA ATV Programme Manager) and Nicolas

Chamussy (Astrium ATV Programme

Director) on the programme.

The Pre-Shipment Review was held at ESA’s

premises in Les Mureaux (F) on 4 July. This

review confirmed that all the required work

had been performed on the spacecraft in

Europe, giving the green light to ship it to the

launch site in Kourou, French Guiana. The

spacecraft and all its ground support

equipment, with a total weight of 400 t, left

Rotterdam in mid-July. Once in Kourou, at

the end of July, the launch campaign testing

and integration continued. The launch

schedule was revised to allow for the ‘heavy

traffic’ to the ISS at the end of the year and

will now be no earlier than January 2008.

Meanwhile, the System Qualification Review

is well underway, with the board meeting

planned for September.

After delivery of the new version of the

Russian Service Module Simulator, the ATV

Control Centre is preparing to support the

Joint Integrated Simulations Programme now

established with NASA and Roskosmos.

Engineering support tools were exercised

during the ATV System Validation Test and

the ATV Cargo Safety Review was conducted.

Columbus spares, for launch on the first ATV,

have been identified and are being prepared

for delivery. The spares will be stowed

aboard the ISS to improve Columbus

availability and reduce future upload

transportation costs.

At KSC, the Columbus system checkout test

was followed by the final modifications and

adjustments to the payload racks, including

the final integration of the Canadian Space

Agency-developed Microgravity Vibration

Isolation System into the Fluid Science

Laboratory (FSL) of Columbus. The EuTEF

and Solar external payload packages are in

the final stages of acceptance and will be

shipped to KSC this summer. The FlyWheel

Exercise Device, GEOFLOW and WAICO

experiments, to be performed standalone and

in the Biolab and FSL racks, respectively, are

integrated in the European Transport Carrier

rack. WAICO is expected to be delivered to

KSC by September for Shuttle mid-deck

stowage.

The Columbus Control Centre (COL-CC)

development contract was completed;

COL-CC is now maintained as a part of the

ISS Operations Services Contract. The

operations qualification, training and

simulations programmes for both ATV and

Columbus are progressing on schedule.

Node-2 ‘Harmony’, having completed close-

out, is in the cleanroom at KSC with its hatch

closed waiting for integration and preparation

for launch in October. Node-3, having

completed its Element Leak Test, Engineering

Review and Preliminary Acceptance Review,

will be maintained in Europe, at the request

of NASA, until mid-2009. Once delivered to

KSC in 2009, it will undergo flight close-out

and then be integrated with Cupola (currently

stored at KSC) for launch together in late

spring 2010.

Utilisation

A debriefing of the AstroLab mission

operations was held at COL-CC, with the

participation of all the parties, with the prime

ATV begins its journey to the launch site

The configuration of the ISS as STS-117 left in June 2007

The Columbus Control Centre

BPb131.qxd 8/1/07 5:11 PM Page 60

esa bulletin 131 - august 2007www.esa.int 63

In ProgressProgrammes

62 esa bulletin 131 - august 2007 www.esa.int

Columbus module to the ISS. Schlegel has,

so far, participated in three 2-hour sessions

in the Neutral Buoyancy Facility (NBF),

training to carry out the various EVA

practices and many emergency and safety

drills, in preparation for his part in the

docking of Columbus to the ISS.

Léopold Eyharts (F) was been named as an

ISS crewmember for STS-122, with Frank

De Winne (B) as his backup. Eyharts will be

staying aboard the ISS for about 3 months to

help commission Columbus and its payload

facilities. He is due to return to Earth aboard

STS-123 in February 2008.

Both Eyharts and De Winne underwent

Columbus specialist training at the European

Astronaut Centre followed, during the second

week in May, by Special Purpose Dextrous

Manipulator training at the Canadian Space

Agency. Later in May, they both went to the

Gagarin Cosmonaut Training Centre to

practise left-seat Soyuz procedures.

Exploration

At the Programme Board meeting in May, the

Executive presented a working document that

emphasised the importance of converging on

a single ExoMars configuration to secure the

2013 launch date. After a dedicated meeting

on 11 June, the board approved the

Enhanced Baseline Mission: the larger

science payload will accommodate the full

selection of the 16.5 kg Pasteur Payload and

a complete Geophysics/Environment Package

(GEP) of about 30 kg, on a heavy lift

launcher for a 2013 launch. The Request for

Quotation release for Phases-B2/C/D/E1 is

expected in July, having been approved at the

Industrial Policy Committee meeting at the

end of June. It was agreed that there would

be a Baseline Consolidation Review in the

autumn and further discussions would take

place at the HME Programme Board in

November. It is planned that Phase-B2 will

start in January 2008.

Discussions with Roskosmos continue to

consolidate a broad cooperation agreement

on Exploration, including both ExoMars and

the Phobos-Grunt mission. A first joint

meeting, held at the Russian Academy of

Science in Moscow, drew enthusiastic

support from both scientific communities.

A mission design review was held in April for

Phase-A2 of the Mars Sample Return (MSR)

study. The four MSR precursor mission

studies, each lasting 6 months, were kicked

off.

Preparation of the MARS-500 isolation study

in conjunction with the Institute of

Biomedical Problems in Moscow, is

underway with the ‘Call for Candidates’

launched during the Paris Air Show on

constituents, using novel process technology.

The information from this analysis will be an

asset for future long-duration missions.

Preparation of the ESA experiment package

for launch on Soyuz-15 in early October is

proceeding well. ANGKASA, the Malaysian

Space Agency, agreed that their cosmonaut

(Angkasawan is the Malaysian word for

astronaut) will participate in some ESA

medical experiments. In addition, three

biology experiments will fly in a Kubik

incubator and be managed aboard the ISS by

the Russian Increment cosmonaut.

Early in Increment-16, Paolo Nespoli will

perform a set of ASI and ESA science

experiments during mission STS-120/10A,

which also will deploy Node-2.

Foton-M3 payload developments are

completed and Science Verification Tests were

completed in ESTEC’s Microgravity Lab and

Mission Simulation Test in the Erasmus High

Bay. The Payload Flight Models, transported to

TsSKB/Samara during June, are undergoing

payload integration in the carrier satellite. In

August, the satellite and its integrated

payloads will be transported to the Baikonur

Cosmodrome, with a scheduled launch date of

17 September for a 12-day mission.

Astronauts

On 26 April, Thomas Reiter participated in a

joint European Commission/ESA press

conference in Brussels, along with EC Vice-

President Günter Verheugen and ESA’s

Director General, for the announcement of the

European Space Policy, prior to the official

adoption by the EC on 22 May.

Thomas Reiter and Christer Fuglesang

(Celsius Mission) continue to be in demand

for post-flight activities.

After the signature of the ESA/ASI agreement,

work continues on the finalisation of the Joint

Implementation Plan, the Joint

Communication Plan and the Joint Education

Plan. Paolo Nespoli is continuing his training

at NASA’s Johnson Space Center.

Hans Schlegel (D) continues training for his

flight on STS-122 (1E), which will deliver the

19 June. The final selection of candidates is

due to be concluded by November.

The evaluation of all proposals received for

the Architecture Studies was completed.

ESA and the European Science Foundation

organised a workshop held on 15–16 May in

Athens. Scientists from 11 European

countries agreed on the science goals for

Europe’s future planetary exploration

programme. The draft recommendations

provide an ambitious roadmap to examine

Mars, the Moon and Near-Earth Objects.

Having been presented to the second

meeting of the Advisory Committee for

Human Spaceflight, Microgravity and

Exploration Programmes, the development

status of the ‘European long-term strategy

for Space’ was presented at the ‘Sky and

Space Intergroup’ meeting of the European

Parliament, in Strasbourg, to the HME

Programme Board on 23 May and to the

Council of ESA.

Authorisations to Proceed were placed for

both the system and the breadboarding

activities for the Crew Space Transportation

System (CSTS) to allow exchanges with the

Russian counterpart. The short-term

activities of CSTS were discussed and agreed

with Roskosmos to place Russian industry

under contract and allow them to work with

European industry. A draft understanding is

under development between JAXA and ESA

to cover participation in CSTS.

Vega

Following the System CDR board on 2 April,

an action plan was set up, leading to the

closure of the review by end-September.

The acceptance campaign of the Zefiro-23

QM1 structure was concluded with the

completion of the compression test on

The Pasteur instrument exobiology payload on ExoMars willinclude a drill that will be able to look for traces of life formsbeneath the surface of Mars

Paolo Nespoli at the Kennedy Space Center

24 April. Several milestones were reached in

the reporting period: the PDR of the modified

interstage-1/2, acceptance of the

interstage-2/3 Qualification Model (QM), and

the Manufacturing Readiness Reviews of the

Zefiro-23 QM case and the Zefiro-9 QM2

case. Preparation of the P80 QM firing test is

under way; the nozzle has been formally

accepted.

For the ground segment, the second sector of

the mobile gantry was completed.

Soyuz at CSG

The CDR for the laucher, which started in

March, concluded in May. The tests of the ‘Kit

Sauvegarde Europe’ were completed in April.

After the Soyuz Launch Base was officially

inaugurated on 26 February, construction

continues on schedule.

The schedule of the Russian contributions is

under revision by the Russian contractor, who

will deliver inputs for schedule consolidation

by June. The main critical aspects have been

identified and might generate a delay of

3 months at most on the launch date. Efforts

are in place to minimise the effects, with the

goal of keeping of keeping to the launch date.

FLPP

All activities are proceeding after the

Consolidated Contract integrating all

remaining activities from FLPP-1 was signed.

The proposal for the first set of activities on

the High Thrust Engine was received; the

Technical Assistance Agreements were drafted

and approved by the Launchers Programme

Board. The Preliminary Requirements Review

for the Intermedidate Experimental Vehicle

was accomplished.

A Contract Change Notice for continuation of

the first set of activities and bridging with the

second set relevant to the Cryogenic

Reignitable Upper Stage Engine – Expander

Demonstrator was committed. ed

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esa bulletin 131 - august 2007www.esa.int 63

In ProgressProgrammes

62 esa bulletin 131 - august 2007 www.esa.int

Columbus module to the ISS. Schlegel has,

so far, participated in three 2-hour sessions

in the Neutral Buoyancy Facility (NBF),

training to carry out the various EVA

practices and many emergency and safety

drills, in preparation for his part in the

docking of Columbus to the ISS.

Léopold Eyharts (F) was been named as an

ISS crewmember for STS-122, with Frank

De Winne (B) as his backup. Eyharts will be

staying aboard the ISS for about 3 months to

help commission Columbus and its payload

facilities. He is due to return to Earth aboard

STS-123 in February 2008.

Both Eyharts and De Winne underwent

Columbus specialist training at the European

Astronaut Centre followed, during the second

week in May, by Special Purpose Dextrous

Manipulator training at the Canadian Space

Agency. Later in May, they both went to the

Gagarin Cosmonaut Training Centre to

practise left-seat Soyuz procedures.

Exploration

At the Programme Board meeting in May, the

Executive presented a working document that

emphasised the importance of converging on

a single ExoMars configuration to secure the

2013 launch date. After a dedicated meeting

on 11 June, the board approved the

Enhanced Baseline Mission: the larger

science payload will accommodate the full

selection of the 16.5 kg Pasteur Payload and

a complete Geophysics/Environment Package

(GEP) of about 30 kg, on a heavy lift

launcher for a 2013 launch. The Request for

Quotation release for Phases-B2/C/D/E1 is

expected in July, having been approved at the

Industrial Policy Committee meeting at the

end of June. It was agreed that there would

be a Baseline Consolidation Review in the

autumn and further discussions would take

place at the HME Programme Board in

November. It is planned that Phase-B2 will

start in January 2008.

Discussions with Roskosmos continue to

consolidate a broad cooperation agreement

on Exploration, including both ExoMars and

the Phobos-Grunt mission. A first joint

meeting, held at the Russian Academy of

Science in Moscow, drew enthusiastic

support from both scientific communities.

A mission design review was held in April for

Phase-A2 of the Mars Sample Return (MSR)

study. The four MSR precursor mission

studies, each lasting 6 months, were kicked

off.

Preparation of the MARS-500 isolation study

in conjunction with the Institute of

Biomedical Problems in Moscow, is

underway with the ‘Call for Candidates’

launched during the Paris Air Show on

constituents, using novel process technology.

The information from this analysis will be an

asset for future long-duration missions.

Preparation of the ESA experiment package

for launch on Soyuz-15 in early October is

proceeding well. ANGKASA, the Malaysian

Space Agency, agreed that their cosmonaut

(Angkasawan is the Malaysian word for

astronaut) will participate in some ESA

medical experiments. In addition, three

biology experiments will fly in a Kubik

incubator and be managed aboard the ISS by

the Russian Increment cosmonaut.

Early in Increment-16, Paolo Nespoli will

perform a set of ASI and ESA science

experiments during mission STS-120/10A,

which also will deploy Node-2.

Foton-M3 payload developments are

completed and Science Verification Tests were

completed in ESTEC’s Microgravity Lab and

Mission Simulation Test in the Erasmus High

Bay. The Payload Flight Models, transported to

TsSKB/Samara during June, are undergoing

payload integration in the carrier satellite. In

August, the satellite and its integrated

payloads will be transported to the Baikonur

Cosmodrome, with a scheduled launch date of

17 September for a 12-day mission.

Astronauts

On 26 April, Thomas Reiter participated in a

joint European Commission/ESA press

conference in Brussels, along with EC Vice-

President Günter Verheugen and ESA’s

Director General, for the announcement of the

European Space Policy, prior to the official

adoption by the EC on 22 May.

Thomas Reiter and Christer Fuglesang

(Celsius Mission) continue to be in demand

for post-flight activities.

After the signature of the ESA/ASI agreement,

work continues on the finalisation of the Joint

Implementation Plan, the Joint

Communication Plan and the Joint Education

Plan. Paolo Nespoli is continuing his training

at NASA’s Johnson Space Center.

Hans Schlegel (D) continues training for his

flight on STS-122 (1E), which will deliver the

19 June. The final selection of candidates is

due to be concluded by November.

The evaluation of all proposals received for

the Architecture Studies was completed.

ESA and the European Science Foundation

organised a workshop held on 15–16 May in

Athens. Scientists from 11 European

countries agreed on the science goals for

Europe’s future planetary exploration

programme. The draft recommendations

provide an ambitious roadmap to examine

Mars, the Moon and Near-Earth Objects.

Having been presented to the second

meeting of the Advisory Committee for

Human Spaceflight, Microgravity and

Exploration Programmes, the development

status of the ‘European long-term strategy

for Space’ was presented at the ‘Sky and

Space Intergroup’ meeting of the European

Parliament, in Strasbourg, to the HME

Programme Board on 23 May and to the

Council of ESA.

Authorisations to Proceed were placed for

both the system and the breadboarding

activities for the Crew Space Transportation

System (CSTS) to allow exchanges with the

Russian counterpart. The short-term

activities of CSTS were discussed and agreed

with Roskosmos to place Russian industry

under contract and allow them to work with

European industry. A draft understanding is

under development between JAXA and ESA

to cover participation in CSTS.

Vega

Following the System CDR board on 2 April,

an action plan was set up, leading to the

closure of the review by end-September.

The acceptance campaign of the Zefiro-23

QM1 structure was concluded with the

completion of the compression test on

The Pasteur instrument exobiology payload on ExoMars willinclude a drill that will be able to look for traces of life formsbeneath the surface of Mars

Paolo Nespoli at the Kennedy Space Center

24 April. Several milestones were reached in

the reporting period: the PDR of the modified

interstage-1/2, acceptance of the

interstage-2/3 Qualification Model (QM), and

the Manufacturing Readiness Reviews of the

Zefiro-23 QM case and the Zefiro-9 QM2

case. Preparation of the P80 QM firing test is

under way; the nozzle has been formally

accepted.

For the ground segment, the second sector of

the mobile gantry was completed.

Soyuz at CSG

The CDR for the laucher, which started in

March, concluded in May. The tests of the ‘Kit

Sauvegarde Europe’ were completed in April.

After the Soyuz Launch Base was officially

inaugurated on 26 February, construction

continues on schedule.

The schedule of the Russian contributions is

under revision by the Russian contractor, who

will deliver inputs for schedule consolidation

by June. The main critical aspects have been

identified and might generate a delay of

3 months at most on the launch date. Efforts

are in place to minimise the effects, with the

goal of keeping of keeping to the launch date.

FLPP

All activities are proceeding after the

Consolidated Contract integrating all

remaining activities from FLPP-1 was signed.

The proposal for the first set of activities on

the High Thrust Engine was received; the

Technical Assistance Agreements were drafted

and approved by the Launchers Programme

Board. The Preliminary Requirements Review

for the Intermedidate Experimental Vehicle

was accomplished.

A Contract Change Notice for continuation of

the first set of activities and bridging with the

second set relevant to the Cryogenic

Reignitable Upper Stage Engine – Expander

Demonstrator was committed. ed

BPb131.qxd 8/1/07 5:11 PM Page 62

www.esa.intwww.esa.int esa bulletin 131 - august 2007esa bulletin 131 - august 2007 6564

In Brief

In Brief

ESA and Inmarsat moved closer

in June to Alphasat, the first

satellite based on Alphabus, the

new European multi-purpose

platform for the high-power

communications satellite

market.

Alphasat will use the Alphabus

proto-flight platform,

providing in-orbit validation of

the platform through a

commercial operator. ESA and

Inmarsat have signed a

Memorandum of Understanding

as the first step towards

confirming Inmarsat as the

platform’s first customer.

Inmarsat intends to fly an

extended L-band payload in

support of its global mobile

services. The satellite will be

positioned at 25ºE to cover

Africa, Europe, the Middle-East

and parts of Asia.

News

This ‘Geo-mobile’ application

requires a 90º change to the flight

orientation to accommodate the

large deployed reflector and its

feed. In addition, Alphasat will

carry three ESA technology

payloads: an advanced startracker

using active pixel technology, an

optical laser terminal for

geostationary to low-Earth orbit

communication at high rates, and

a dedicated payload for

Jules Verne, ESA’s first

Automated Transfer Vehicle,

arrived at the Kourou launch site

in French Guiana in late July to

prepare for the final leg of its

journey to the International Space

Station. Launch is planned for

January 2008.

Only 10 days after completing its

final integration and space

environment tests, it left ESTEC

in Noordwijk (NL) on 13 July. The

20 t ATV is the largest and most

complex spacecraft ever built in

Europe. The unmanned ferry will

deliver cargo to the Station and

help to raise its orbit.

A specialised team spent

10 weeks preparing 400 t of

equipment for shipment across

the Atlantic. Each item was

individually documented and

carefully packed into around 50

containers. “One of the major

issues has been getting the

customs paperwork in order,”

explains Stefan Brosze, ATV

Transportation Manager. “There

are members of our team who

know exactly where to find

everything, right down to the very

smallest items.”

Alphasat configured for the

Inmarsat-XL mission

Left: ATV is prepared for its departure fromEurope. The spacecraft was shipped in threemajor sections

characterising transmission

performance in the Q–V band in

preparation for possible

commercial exploitation of these

frequencies.

The intention is to begin the

programme in the third quarter of

2007, with launch in 2011. e

ATV On Its Way

ATV was taken by lorry and canal

barge to Rotterdam harbour and

loaded aboard the MN Toucan, a

vessel normally used by

Arianespace to transport Ariane

rocket components on the same

route across the Atlantic. e

After 5 years of work, the YES2

second Young Engineers Satellite

experiment is ready for launch.

The successful Final Acceptance

Review on 20 June gave the green

light for launch in September

attached to the Foton-M3

spacecraft. YES2 will deploy a

small recoverable capsule on a

30 km tether – the longest ever

used in space – for reentry

without rocket propulsion. This

first descent via tether will pave

the way for the low-cost return-to-

Earth for future payloads.

Following 4.5 months of

assembly, integration and testing

YES to Launch Site

at ESTEC, the groundbreaking

student experiment was shipped

on 7 May to TsSKB-Progress, the

Foton prime contractor, in

Samara, Russia. On 14 June, the

payload was installed on the

exterior of Foton-M3 to begin

weeks of tests.

“Although there were tight

deadlines to meet, the students

worked closely in conjunction

with ESA and prime contractor

Delta-Utec to get it ready to

launch,” said Roger Walker,

Project Manager for YES2, from

the ESA Education Office. “It has

completed an intensive

Right: the 5.5 kg, 40 cm-diameter YES2 capsulewill be the first space payload to use a tether tobegin its return to Earth

verification campaign, involving

vibration testing, thermal-vacuum

and electromagnetic testing. The

team has achieved a great deal to

get this far, and the students have

benefited tremendously from this

practical experience with a real

space project.”

Following the final tests, YES2

was removed and shipped to

Baikonur Cosmodrome in early

July, where it met its host

spacecraft again at the end of the

month.

Almost 500 students from most

ESA Member States, plus the

United States, Japan, Canada and

Australia, have worked on YES2.

Although these were mainly

involved in the preliminary

design, some 60 students

developed and built hardware and

software. e

EGNOS and Other Satnav for Africa

ESA and the Agency for Security

of Air Navigation in Africa and

Madagascar signed a cooperation

agreement on 22 June with the

objective of using satellite

navigation to improve air traffic

safety over the African continent.

The agreement, which covers

cooperation between ESA and the

African aviation safety agency

(Agence pour la Sécurité de la

Navigation Aérienne en Afrique –

ASECNA), focuses on the next

phase of Global Navigation

Satellite Systems (GNSS)

deployment, which includes the

extension and use of the

European Geostationary

Navigation Overlay Service

(EGNOS) as an operational

service in Africa.

The agreement envisages ESA

and ASECNA providing mutual

assistance, notably with regard to

extending EGNOS operational

services more widely in Africa,

siting European ground

installations in ASECNA

countries, supporting the project

in international standardisation

bodies and bringing Galileo

services and additional elements

to Africa.

ESA and ASECNA have been

working together since 2003 and

have organised several test

campaigns that clearly

demonstrated the benefits of

EGNOS for Africa, where very few

airports are equipped with

conventional landing guidance

systems.

For these campaigns, ASECNA

provided its calibration aircraft

and hosted and operated EGNOS

stations at several African

A wealth of new mission

concepts was submitted by the

European scientific community by

29 June, following the ESA Call

for Proposals in March. The

proposals cover a wide variety of

scientific objectives, from the

search for extrasolar planets, the

study of Jupiter and its icy

satellite Europa, to testing the

laws of gravity.

The missions’ objectives fit well

with the four major themes of

ESA’s Cosmic Vision 2015–2025

plan: the conditions for life and

planetary formation; the origin

and formation of the Solar

System; the fundamental laws of

the cosmos; the origin, structure

and evolution of the Universe.

Out of these 50 concepts, three

medium missions (with cost to

ESA within EUR300 million) and

three large missions (costs to

ESA within EUR650 million) will

be selected for assessment

starting in October this year.

The evaluation process will treat

the scientific value and novelty of

the proposal as the main criteria,

together with the technological

maturity and estimated cost.

At the end of the full assessment

cycle in 2011, one medium and

one large mission will be adopted

for implementation by ESA’s

Science Programme Committee.

Their launches are expected in

2017 and 2018, respectively. e

50 Science Mission Proposals

Alphabus First Mission

B131inbrief 8/1/07 5:12 PM Page 64

www.esa.intwww.esa.int esa bulletin 131 - august 2007esa bulletin 131 - august 2007 6564

In Brief

In Brief

ESA and Inmarsat moved closer

in June to Alphasat, the first

satellite based on Alphabus, the

new European multi-purpose

platform for the high-power

communications satellite

market.

Alphasat will use the Alphabus

proto-flight platform,

providing in-orbit validation of

the platform through a

commercial operator. ESA and

Inmarsat have signed a

Memorandum of Understanding

as the first step towards

confirming Inmarsat as the

platform’s first customer.

Inmarsat intends to fly an

extended L-band payload in

support of its global mobile

services. The satellite will be

positioned at 25ºE to cover

Africa, Europe, the Middle-East

and parts of Asia.

News

This ‘Geo-mobile’ application

requires a 90º change to the flight

orientation to accommodate the

large deployed reflector and its

feed. In addition, Alphasat will

carry three ESA technology

payloads: an advanced startracker

using active pixel technology, an

optical laser terminal for

geostationary to low-Earth orbit

communication at high rates, and

a dedicated payload for

Jules Verne, ESA’s first

Automated Transfer Vehicle,

arrived at the Kourou launch site

in French Guiana in late July to

prepare for the final leg of its

journey to the International Space

Station. Launch is planned for

January 2008.

Only 10 days after completing its

final integration and space

environment tests, it left ESTEC

in Noordwijk (NL) on 13 July. The

20 t ATV is the largest and most

complex spacecraft ever built in

Europe. The unmanned ferry will

deliver cargo to the Station and

help to raise its orbit.

A specialised team spent

10 weeks preparing 400 t of

equipment for shipment across

the Atlantic. Each item was

individually documented and

carefully packed into around 50

containers. “One of the major

issues has been getting the

customs paperwork in order,”

explains Stefan Brosze, ATV

Transportation Manager. “There

are members of our team who

know exactly where to find

everything, right down to the very

smallest items.”

Alphasat configured for the

Inmarsat-XL mission

Left: ATV is prepared for its departure fromEurope. The spacecraft was shipped in threemajor sections

characterising transmission

performance in the Q–V band in

preparation for possible

commercial exploitation of these

frequencies.

The intention is to begin the

programme in the third quarter of

2007, with launch in 2011. e

ATV On Its Way

ATV was taken by lorry and canal

barge to Rotterdam harbour and

loaded aboard the MN Toucan, a

vessel normally used by

Arianespace to transport Ariane

rocket components on the same

route across the Atlantic. e

After 5 years of work, the YES2

second Young Engineers Satellite

experiment is ready for launch.

The successful Final Acceptance

Review on 20 June gave the green

light for launch in September

attached to the Foton-M3

spacecraft. YES2 will deploy a

small recoverable capsule on a

30 km tether – the longest ever

used in space – for reentry

without rocket propulsion. This

first descent via tether will pave

the way for the low-cost return-to-

Earth for future payloads.

Following 4.5 months of

assembly, integration and testing

YES to Launch Site

at ESTEC, the groundbreaking

student experiment was shipped

on 7 May to TsSKB-Progress, the

Foton prime contractor, in

Samara, Russia. On 14 June, the

payload was installed on the

exterior of Foton-M3 to begin

weeks of tests.

“Although there were tight

deadlines to meet, the students

worked closely in conjunction

with ESA and prime contractor

Delta-Utec to get it ready to

launch,” said Roger Walker,

Project Manager for YES2, from

the ESA Education Office. “It has

completed an intensive

Right: the 5.5 kg, 40 cm-diameter YES2 capsulewill be the first space payload to use a tether tobegin its return to Earth

verification campaign, involving

vibration testing, thermal-vacuum

and electromagnetic testing. The

team has achieved a great deal to

get this far, and the students have

benefited tremendously from this

practical experience with a real

space project.”

Following the final tests, YES2

was removed and shipped to

Baikonur Cosmodrome in early

July, where it met its host

spacecraft again at the end of the

month.

Almost 500 students from most

ESA Member States, plus the

United States, Japan, Canada and

Australia, have worked on YES2.

Although these were mainly

involved in the preliminary

design, some 60 students

developed and built hardware and

software. e

EGNOS and Other Satnav for Africa

ESA and the Agency for Security

of Air Navigation in Africa and

Madagascar signed a cooperation

agreement on 22 June with the

objective of using satellite

navigation to improve air traffic

safety over the African continent.

The agreement, which covers

cooperation between ESA and the

African aviation safety agency

(Agence pour la Sécurité de la

Navigation Aérienne en Afrique –

ASECNA), focuses on the next

phase of Global Navigation

Satellite Systems (GNSS)

deployment, which includes the

extension and use of the

European Geostationary

Navigation Overlay Service

(EGNOS) as an operational

service in Africa.

The agreement envisages ESA

and ASECNA providing mutual

assistance, notably with regard to

extending EGNOS operational

services more widely in Africa,

siting European ground

installations in ASECNA

countries, supporting the project

in international standardisation

bodies and bringing Galileo

services and additional elements

to Africa.

ESA and ASECNA have been

working together since 2003 and

have organised several test

campaigns that clearly

demonstrated the benefits of

EGNOS for Africa, where very few

airports are equipped with

conventional landing guidance

systems.

For these campaigns, ASECNA

provided its calibration aircraft

and hosted and operated EGNOS

stations at several African

A wealth of new mission

concepts was submitted by the

European scientific community by

29 June, following the ESA Call

for Proposals in March. The

proposals cover a wide variety of

scientific objectives, from the

search for extrasolar planets, the

study of Jupiter and its icy

satellite Europa, to testing the

laws of gravity.

The missions’ objectives fit well

with the four major themes of

ESA’s Cosmic Vision 2015–2025

plan: the conditions for life and

planetary formation; the origin

and formation of the Solar

System; the fundamental laws of

the cosmos; the origin, structure

and evolution of the Universe.

Out of these 50 concepts, three

medium missions (with cost to

ESA within EUR300 million) and

three large missions (costs to

ESA within EUR650 million) will

be selected for assessment

starting in October this year.

The evaluation process will treat

the scientific value and novelty of

the proposal as the main criteria,

together with the technological

maturity and estimated cost.

At the end of the full assessment

cycle in 2011, one medium and

one large mission will be adopted

for implementation by ESA’s

Science Programme Committee.

Their launches are expected in

2017 and 2018, respectively. e

50 Science Mission Proposals

Alphabus First Mission

B131inbrief 8/1/07 5:12 PM Page 64

www.esa.intwww.esa.intesa bulletin 131 - august 200766

News

The High Resolution Stereo Cameraof Mars Express imaged the AeolisMensae region (6ºS/145ºE) of theRed Planet on 26 and 29 March2007. Deep valleys are incised intothe highlands with unexplained linearfeatures on some floors.(ESA/DLR/FU Berlin, G. Neukum)

European engineers are

developing increasingly

sophisticated machines to work

in space. ESA’s ‘Eurobot’ recently

completed trials in the giant

pool at the European Astronaut

Centre.

Eurobot has been under

development since 2003, with the

intention that the multi-jointed,

three-armed assistant will

eventually handle some of the

more mundane tasks currently

undertaken by astronauts on

spacewalks. It may also be an

indispensable helper on

expeditions to the Moon or Mars.

In the hostile conditions of space,

the tireless Eurobot will save a

great deal of time and effort by

taking over routine tasks. For

example, the astronauts’ flexible

friend will be able to find its way

to a worksite on the International

Space Station (ISS), perform a

close-up inspection and carry out

preparatory work, such as

transferring tools and equipment.

Remotely controlled by an

operator inside the ISS, Eurobot

can multi-task, providing

additional hands and eyes for the

spacewalkers. Once the

astronauts are safely inside the

Station, Eurobot will clear away

the tools and equipment.

Eurobot is lowered into the pool for ‘weightless’ testing

airports. This is how the first

crossing of Africa at its widest

part, from Dakar to Mombasa,

was achieved in May 2005, using

EGNOS signals.

Composed of a network of

around 40 elements distributed

across Europe to record, correct

and improve data from GPS,

EGNOS provides modified signals

relayed by geostationary satellites

to users’ receivers. It offers an

accuracy of better than 2 m,

compared with the 15–20 m for

GPS signals, with an added

guarantee of signal quality.

Since the geostationary satellites

that relay EGNOS also cover

Africa, an extension of EGNOS

may easily be envisaged with the

installation of reference stations

on African soil. e

ESA signed two key contracts

with NGL Prime S.p.A. of Italy in

June: the definition of launcher

concepts for the European Next

Generation Launcher, and the

development of the European

Intermediate eXperimental

Vehicle (IXV). Both are part of

ESA’s Future Launchers

Preparatory Programme (FLPP),

which is aiming to develop and

demonstrate the technologies for

Two new launcher contracts were signed by ESA’s Director of Launcher Programmes, AntonioFabrizi (left), and Axel Roenneke, CEO of NGLPrime S.p.A.

At a ceremony in Tallinn on

20 June, René Oosterlinck, ESA

Director of Legal Affairs and

External Relations, and Juhan

Parts, Estonian Minister of

Economic Affairs and

Communications, signed an

agreement marking closer

cooperation between ESA and

Estonia.

Estonia is the first of the

countries that have recently

joined the European Union to

sign a Cooperation Agreement

with ESA. Andrus Ansip, Prime

Minister of Estonia, welcomed the

ESA delegation and confirmed the

support his government is ready

to give to this new agreement.

A first meeting with an Estonian

delegation took place at the

beginning of 2006 at ESA’s

headquarters in Paris. This was

followed by an invitation by the

Minister of Economic Affairs and

Communications to send an ESA

delegation to Tallinn in November

2006, to explain in more detail

Estonia Agreement

the different types of cooperation

between ESA and non-ESA

Member States, and to meet with

potential partners.

Estonia has long-standing

experience in astronomy and

space science. The Observatory

of Tartu has worked in this field

since the 19th century, and is

participating in preparations for

ESA’s Planck and Gaia missions.

The recent adoption of the

European Space Policy by ESA

and the EU confirms the

importance of ESA’s space

activities for EU Member States.

New members of the EU are now

approaching ESA with a view to

participating in ESA’s space

activities.

This Cooperation Agreement is a

first step. As a second step,

Estonia intends to become a

European Cooperating State in a

few years with an increased

financial contribution to space

activities. e

Eurobot: Astronauts’ Assistant

project team gained experience of

the robot’s capabilities, trying out

multi-arm control and

coordination, along with visual

recognition of obscured targets.

Eurobot was joined in the pool by

ESA astronaut Jean-François

Clervoy to demonstrate the

interaction between astronaut and

robot.

The trials concluded the initial

verification phase of the Eurobot

WET model programme,

following on from preliminary dry

and wet tests in Italy.

“The tests went very well,” said

Philippe Schoonejans, ESA’s

Eurobot Project Manager. “Not

only has it been demonstrated

that Eurobot can walk around an

orbital station autonomously and

safely, using no more than the

existing EVA handrails, it is also

becoming clear that Eurobot can

really help the astronauts. And in

the next phase we also plan to

demonstrate its use on a

planetary surface, as part of the

Agency’s exploration

programme.” e

a Next Generation Launcher

(NGL) for Europe, expected to

become operational after 2020. A

secondary aim is to increase the

reliability and competitiveness of

European launchers, including

those operational today.

The contracts have a total value

of more than EUR20 million and

integrate key European

competences and expertise in

launcher and reentry systems

from 43 industrial and research

organisations from 11 ESA

member states.

The launcher systems studies will

prepare key technical and

programme data for the ESA

Ministerial Conference in 2008,

when strategic decisions about

future launcher development will

be made. The studies will

examine the different options that

Europe could adopt for the NGL.

In parallel, the IXV will

demonstrate Europe’s advanced

reentry technologies and

integrated system design

capabilities. The IXV reference

mission calls for launch from

Kourou in 2010 aboard a Vega

vehicle, followed by a fully

automatic reentry, descent and

landing in the Pacific Ocean.e

“It could be a most useful aid,”

said Gianfranco Visentin, head of

ESA’s Automation and Robotics

section. “There is a shortage of

crew time during all missions, so

anything that improves the use of

astronaut time is very desirable.”

The version of Eurobot used in

July’s exercises was the

Weightless Environmental Test

(WET) early prototype, developed

for operation in a water tank

where the microgravity conditions

of space are simulated.

Developed for ESA by a

consortium led by Thales Alenia

Space, the WET model has a

central body with three identical

arms, each with seven joints.

Although the arms’ length and

strength are similar to those of a

human, they are much more

manoeuvrable and versatile.

Each arm carries a camera and an

‘end-effector’ hand. The WET

model has only one type of hand,

which is capable of grasping EVA

handrails. In contrast, the real

Eurobot will have a set of three or

four interchangeable hands. A

head camera monitors the

worksite.

During tests of its ability to move

and manipulate objects, the

Launcher Contracts

67esa bulletin 131 - august 2007

B131inbrief 8/1/07 5:12 PM Page 66

www.esa.intwww.esa.intesa bulletin 131 - august 200766

News

The High Resolution Stereo Cameraof Mars Express imaged the AeolisMensae region (6ºS/145ºE) of theRed Planet on 26 and 29 March2007. Deep valleys are incised intothe highlands with unexplained linearfeatures on some floors.(ESA/DLR/FU Berlin, G. Neukum)

European engineers are

developing increasingly

sophisticated machines to work

in space. ESA’s ‘Eurobot’ recently

completed trials in the giant

pool at the European Astronaut

Centre.

Eurobot has been under

development since 2003, with the

intention that the multi-jointed,

three-armed assistant will

eventually handle some of the

more mundane tasks currently

undertaken by astronauts on

spacewalks. It may also be an

indispensable helper on

expeditions to the Moon or Mars.

In the hostile conditions of space,

the tireless Eurobot will save a

great deal of time and effort by

taking over routine tasks. For

example, the astronauts’ flexible

friend will be able to find its way

to a worksite on the International

Space Station (ISS), perform a

close-up inspection and carry out

preparatory work, such as

transferring tools and equipment.

Remotely controlled by an

operator inside the ISS, Eurobot

can multi-task, providing

additional hands and eyes for the

spacewalkers. Once the

astronauts are safely inside the

Station, Eurobot will clear away

the tools and equipment.

Eurobot is lowered into the pool for ‘weightless’ testing

airports. This is how the first

crossing of Africa at its widest

part, from Dakar to Mombasa,

was achieved in May 2005, using

EGNOS signals.

Composed of a network of

around 40 elements distributed

across Europe to record, correct

and improve data from GPS,

EGNOS provides modified signals

relayed by geostationary satellites

to users’ receivers. It offers an

accuracy of better than 2 m,

compared with the 15–20 m for

GPS signals, with an added

guarantee of signal quality.

Since the geostationary satellites

that relay EGNOS also cover

Africa, an extension of EGNOS

may easily be envisaged with the

installation of reference stations

on African soil. e

ESA signed two key contracts

with NGL Prime S.p.A. of Italy in

June: the definition of launcher

concepts for the European Next

Generation Launcher, and the

development of the European

Intermediate eXperimental

Vehicle (IXV). Both are part of

ESA’s Future Launchers

Preparatory Programme (FLPP),

which is aiming to develop and

demonstrate the technologies for

Two new launcher contracts were signed by ESA’s Director of Launcher Programmes, AntonioFabrizi (left), and Axel Roenneke, CEO of NGLPrime S.p.A.

At a ceremony in Tallinn on

20 June, René Oosterlinck, ESA

Director of Legal Affairs and

External Relations, and Juhan

Parts, Estonian Minister of

Economic Affairs and

Communications, signed an

agreement marking closer

cooperation between ESA and

Estonia.

Estonia is the first of the

countries that have recently

joined the European Union to

sign a Cooperation Agreement

with ESA. Andrus Ansip, Prime

Minister of Estonia, welcomed the

ESA delegation and confirmed the

support his government is ready

to give to this new agreement.

A first meeting with an Estonian

delegation took place at the

beginning of 2006 at ESA’s

headquarters in Paris. This was

followed by an invitation by the

Minister of Economic Affairs and

Communications to send an ESA

delegation to Tallinn in November

2006, to explain in more detail

Estonia Agreement

the different types of cooperation

between ESA and non-ESA

Member States, and to meet with

potential partners.

Estonia has long-standing

experience in astronomy and

space science. The Observatory

of Tartu has worked in this field

since the 19th century, and is

participating in preparations for

ESA’s Planck and Gaia missions.

The recent adoption of the

European Space Policy by ESA

and the EU confirms the

importance of ESA’s space

activities for EU Member States.

New members of the EU are now

approaching ESA with a view to

participating in ESA’s space

activities.

This Cooperation Agreement is a

first step. As a second step,

Estonia intends to become a

European Cooperating State in a

few years with an increased

financial contribution to space

activities. e

Eurobot: Astronauts’ Assistant

project team gained experience of

the robot’s capabilities, trying out

multi-arm control and

coordination, along with visual

recognition of obscured targets.

Eurobot was joined in the pool by

ESA astronaut Jean-François

Clervoy to demonstrate the

interaction between astronaut and

robot.

The trials concluded the initial

verification phase of the Eurobot

WET model programme,

following on from preliminary dry

and wet tests in Italy.

“The tests went very well,” said

Philippe Schoonejans, ESA’s

Eurobot Project Manager. “Not

only has it been demonstrated

that Eurobot can walk around an

orbital station autonomously and

safely, using no more than the

existing EVA handrails, it is also

becoming clear that Eurobot can

really help the astronauts. And in

the next phase we also plan to

demonstrate its use on a

planetary surface, as part of the

Agency’s exploration

programme.” e

a Next Generation Launcher

(NGL) for Europe, expected to

become operational after 2020. A

secondary aim is to increase the

reliability and competitiveness of

European launchers, including

those operational today.

The contracts have a total value

of more than EUR20 million and

integrate key European

competences and expertise in

launcher and reentry systems

from 43 industrial and research

organisations from 11 ESA

member states.

The launcher systems studies will

prepare key technical and

programme data for the ESA

Ministerial Conference in 2008,

when strategic decisions about

future launcher development will

be made. The studies will

examine the different options that

Europe could adopt for the NGL.

In parallel, the IXV will

demonstrate Europe’s advanced

reentry technologies and

integrated system design

capabilities. The IXV reference

mission calls for launch from

Kourou in 2010 aboard a Vega

vehicle, followed by a fully

automatic reentry, descent and

landing in the Pacific Ocean.e

“It could be a most useful aid,”

said Gianfranco Visentin, head of

ESA’s Automation and Robotics

section. “There is a shortage of

crew time during all missions, so

anything that improves the use of

astronaut time is very desirable.”

The version of Eurobot used in

July’s exercises was the

Weightless Environmental Test

(WET) early prototype, developed

for operation in a water tank

where the microgravity conditions

of space are simulated.

Developed for ESA by a

consortium led by Thales Alenia

Space, the WET model has a

central body with three identical

arms, each with seven joints.

Although the arms’ length and

strength are similar to those of a

human, they are much more

manoeuvrable and versatile.

Each arm carries a camera and an

‘end-effector’ hand. The WET

model has only one type of hand,

which is capable of grasping EVA

handrails. In contrast, the real

Eurobot will have a set of three or

four interchangeable hands. A

head camera monitors the

worksite.

During tests of its ability to move

and manipulate objects, the

Launcher Contracts

67esa bulletin 131 - august 2007

B131inbrief 8/1/07 5:12 PM Page 66

The appearance of the International Space Station as the latest Space

Shuttle mission, STS-118, arrived in August. The image was captured

on 17 June as STS-117 departed after attaching the S3/4 truss and

solar wings at right. STS-118 will add the S5 segment at right to allow

the S6 solar wings to be attached on a later mission. It will also help

to prepare the way for Europe’s Node-2 and Columbus modules to be

added in October (STS-120) and December (STS-122) this year,

respectively. STS-120 will also move the P6 solar wings (seen here

retracted on top of the Station) to their final position at far left.

ESA’s first Automated Transfer Vehicle is expected to arrive in January

2008, docking with the aft Zvezda module, seen here with a Russian

Progress unmanned ferry attached (closest to camera). Japan’s

Kibo laboratory module and platform will also be installed in 2008.

(NASA)

This Envisat/MERIS image of 2 September 2006 shows the southern

part of the Caspian Sea, at 371 000 square km the world’s largest

inland body of water. The oil-rich Caspian stretches 1200 km north to

south, bordered by Russia and Kazakhstan to the north, Azerbaijan to

the west, Turkmenistan to the east and Iran to the south. Because the

Caspian is a closed body of water, it supports a unique biodiversity but

is also vulnerable to pollution from agriculture and industry –

particularly oil. The Caspian Basin is rich in oil deposits; the oil centre

of Baku, capital of Azerbaijan, is on the southern side of the Apsheron

Peninsula jutting out from the western shore. On the other side of the

sea is Turkmenistan, dominated by the Karakum Desert. On the

southern shores are Iran’s green Gilan-Mazanderan lowlands and the

Alborz mountain range, which hinders rain clouds moving south,

explaining the contrast with the desert to the south.

News In Brief

www.esa.intwww.esa.int esa bulletin 131 - august 2007esa bulletin 131 - august 2007 6968

B131inbrief 8/1/07 5:12 PM Page 68

The appearance of the International Space Station as the latest Space

Shuttle mission, STS-118, arrived in August. The image was captured

on 17 June as STS-117 departed after attaching the S3/4 truss and

solar wings at right. STS-118 will add the S5 segment at right to allow

the S6 solar wings to be attached on a later mission. It will also help

to prepare the way for Europe’s Node-2 and Columbus modules to be

added in October (STS-120) and December (STS-122) this year,

respectively. STS-120 will also move the P6 solar wings (seen here

retracted on top of the Station) to their final position at far left.

ESA’s first Automated Transfer Vehicle is expected to arrive in January

2008, docking with the aft Zvezda module, seen here with a Russian

Progress unmanned ferry attached (closest to camera). Japan’s

Kibo laboratory module and platform will also be installed in 2008.

(NASA)

This Envisat/MERIS image of 2 September 2006 shows the southern

part of the Caspian Sea, at 371 000 square km the world’s largest

inland body of water. The oil-rich Caspian stretches 1200 km north to

south, bordered by Russia and Kazakhstan to the north, Azerbaijan to

the west, Turkmenistan to the east and Iran to the south. Because the

Caspian is a closed body of water, it supports a unique biodiversity but

is also vulnerable to pollution from agriculture and industry –

particularly oil. The Caspian Basin is rich in oil deposits; the oil centre

of Baku, capital of Azerbaijan, is on the southern side of the Apsheron

Peninsula jutting out from the western shore. On the other side of the

sea is Turkmenistan, dominated by the Karakum Desert. On the

southern shores are Iran’s green Gilan-Mazanderan lowlands and the

Alborz mountain range, which hinders rain clouds moving south,

explaining the contrast with the desert to the south.

News In Brief

www.esa.intwww.esa.int esa bulletin 131 - august 2007esa bulletin 131 - august 2007 6968

B131inbrief 8/1/07 5:12 PM Page 68

The interior of the Automated Transfer Vehicle (ATV)

shortly before it was sealed off for the vehicle to be

shipped to its Kourou launch site in July. Launch is

planned for January 2008 on Ariane-5. ATV will

dock with the International Space Station (the

docking mechanism is protected by a red cover at

the far right in the small photograph) with this

pressurised section carrying an array of equipment

and consumables for the crew. Astronauts will enter

via the hatch seen closed in the centre of the large

image. ATV will remain attached for up to 6 months,

periodically raising the Station’s orbit to combat

atmospheric drag, before departing filled with

rubbish to burn up in the atmosphere over the

Pacific Ocean. Other ATV photographs can be seen

on pages 60 and 65. (ESA)

GOCE, ESA’s first satellite dedicated to measuring

the Earth’s gravity field, is seen here at prime

contractor Thales Alenia Space in Turin (I) in July

before being shipped to ESTEC in August. The

‘Gravity field and steady-state Ocean Circulation

Explorer’ will significantly advance our knowledge of

how the Earth works and provide insight into ocean

circulation, sea-level change, climate change,

volcanism and earthquakes. At ESTEC, GOCE will

undergo final integration and environmental testing

to make sure it is ready to withstand the rigours of

launch and space operations. It will be launched

next spring on a Rockot from the Plesetsk

Cosmodrome in north-western Russia. Forty-five

companies from 13 European countries have been

working on the satellite since 2001. (ESA/S. Corvaja)

News In Brief

www.esa.intwww.esa.int esa bulletin 131 - august 2007esa bulletin 131 - august 2007 7170

B131inbrief 8/1/07 5:12 PM Page 70

The interior of the Automated Transfer Vehicle (ATV)

shortly before it was sealed off for the vehicle to be

shipped to its Kourou launch site in July. Launch is

planned for January 2008 on Ariane-5. ATV will

dock with the International Space Station (the

docking mechanism is protected by a red cover at

the far right in the small photograph) with this

pressurised section carrying an array of equipment

and consumables for the crew. Astronauts will enter

via the hatch seen closed in the centre of the large

image. ATV will remain attached for up to 6 months,

periodically raising the Station’s orbit to combat

atmospheric drag, before departing filled with

rubbish to burn up in the atmosphere over the

Pacific Ocean. Other ATV photographs can be seen

on pages 60 and 65. (ESA)

GOCE, ESA’s first satellite dedicated to measuring

the Earth’s gravity field, is seen here at prime

contractor Thales Alenia Space in Turin (I) in July

before being shipped to ESTEC in August. The

‘Gravity field and steady-state Ocean Circulation

Explorer’ will significantly advance our knowledge of

how the Earth works and provide insight into ocean

circulation, sea-level change, climate change,

volcanism and earthquakes. At ESTEC, GOCE will

undergo final integration and environmental testing

to make sure it is ready to withstand the rigours of

launch and space operations. It will be launched

next spring on a Rockot from the Plesetsk

Cosmodrome in north-western Russia. Forty-five

companies from 13 European countries have been

working on the satellite since 2001. (ESA/S. Corvaja)

News In Brief

www.esa.intwww.esa.int esa bulletin 131 - august 2007esa bulletin 131 - august 2007 7170

B131inbrief 8/1/07 5:12 PM Page 70

Publications

72 esa bulletin 131 - august 2007 esa bulletin 131 - august 2007www.esa.int www.esa.int 73

ESA Annual ReportAnnual Report 2006 (July 2007)B. Battrick (Ed.)ESA Annual Report // 126 ppNo Charge

ESA BrochuresESOC (April 2007)D. Danesy (Ed.)ESA BR-265 // 39 ppPrice: 10 Euro

Report by the 2006 Science ProgrammeReview Team to the ESA Council (April 2007)B. Battrick (Ed.)ESA BR-267 // 48 ppPrice: 10 Euro

L. Ouwehand (Ed.)ESA SP-638 // CDPrice: 50 Euro

Proceedings of the 3rd InternationalWorkshop on Science and Applications ofSAR Polarimetry and Interferometry, 22–26January 2007, Frascati, Italy (March 2007)H. Lacoste & L. Ouwehand (Eds.)ESA SP-644 // CDPrice: 50 Euro

Proceedings of the 7th InternationalSymposium ‘Reducing the Costs ofSpacecraft Ground Systems and Operations’(RCSGSO), 11–16 June 2007, Moscow,Russian Federation (July 2007)D. Danesy (Ed.)ESA SP-648 // CD Price: 70 Euro

Proceedings of the 2nd IAASS Conference‘Space Safety in a Global World’, 14-16 May2007, Chicago, USA (July 2007)D. Danesy (Ed.)ESA SP-645 // CD Price: 70 Euro

ESA Contractor ReportsRadio Frequency Transmitter for MultimediaGround Terminals – Final Report (May 2004)ND SatComESA CR(P)-4580 // CDPrice: 25 Euro

SDR Technology in Space – Final Report(June 2006)Atos Origin, SpainESA CR(P)-4583 // CDPrice: 25 Euro

M2 – ASIC System Evolution – Executive Summary (November 2006)Austrian Aerospace, AustriaESA CR(P)-4581 // CDPrice: 25 Euro

Preparation Study of Investigations intoBiological Effects of Radiation – Final Report(December 2006)Univ. of Napels Federico II, ItalyESA CR(P)-4585 // CDPrice: 25 Euro

Minimux – Final Report (October 2006)Tesat, GermanyESA CR(P)-4582 // CDPrice: 25 Euro

LARI – Low Cost Remote Surveillance &Metering Satellite Services Feasibility Study – Final Report & Executive Summary (March 2006)VitroCiset, ItalyESA CR(P)-4584Price: 25 Euro

Multimedia Ground Terminals & Equipment:Fast Forward – Final Report (December2006)Advantech Satellite Networks, CanadaESA CR(P)-4586 // CDPrice: 25 Euro

Breadboarding of Feed Cluster for aReflector-Based Multiple Beam SAR Antenna– Summary Report (January 2007)EADS Astrium GmbH, GermanyESA CR(P)-4587 // CDPrice: 25 Euro

Enhancement of Diffusers BSDF Accuracy – Final Report (November 2007)TNO Science and Industry, The NetherlandsESA CR(P)-4588 // CDPrice: 25 Euro

Satellite Communication System Elements,Technologies and Applications: Opportunitiesfor Start-Up Projects – Executive Summary(June 2004)ComSine Ltd, UKESA CR(P)-4589 // CDPrice: 25 Euro e

New issues

PublicationsThe documents listed here have

been issued since the last

publications announcement in the

ESA Bulletin. Requests for copies

should be made in accordance

with the Table and Order Form

inside the back cover

Resolution on the European Space Policy;ESA Director General’s Proposal for theEuropean Space Policy (June 2007)A. Wilson (Ed.)ESA BR-269 // 37 ppPrice: 10 Euro

ESA NewsletterConnect – ESA TelecommunicationNewsletter (May 2007)N. Menning & P. Clissold (Eds.)No Charge

ESA Special PublicationsBed-Rest Studies in the Spaceflight Era(1986–2005) – A ReviewB. Battrick (Ed.)ESA SP-1305 // 114 ppPrice: 30 Euro

Proceedings of the Envisat Symposium2007, 23–27 April 2007, Montreux,Switzerland (July 2007)H. Lacoste & L. Ouwehand (Eds.)ESA SP-636 // CD (2 volumes)Price: 80 Euro

Proceedings of DASIA 2007, DAta SystemsIn Aerospace, 29 May – 1 June 2007, Naples,Italy (August 2007)

A full listing of ESA publications is available atwww.esa.int/publications

PubsB131 8/1/07 5:13 PM Page 72

Publications

72 esa bulletin 131 - august 2007 esa bulletin 131 - august 2007www.esa.int www.esa.int 73

ESA Annual ReportAnnual Report 2006 (July 2007)B. Battrick (Ed.)ESA Annual Report // 126 ppNo Charge

ESA BrochuresESOC (April 2007)D. Danesy (Ed.)ESA BR-265 // 39 ppPrice: 10 Euro

Report by the 2006 Science ProgrammeReview Team to the ESA Council (April 2007)B. Battrick (Ed.)ESA BR-267 // 48 ppPrice: 10 Euro

L. Ouwehand (Ed.)ESA SP-638 // CDPrice: 50 Euro

Proceedings of the 3rd InternationalWorkshop on Science and Applications ofSAR Polarimetry and Interferometry, 22–26January 2007, Frascati, Italy (March 2007)H. Lacoste & L. Ouwehand (Eds.)ESA SP-644 // CDPrice: 50 Euro

Proceedings of the 7th InternationalSymposium ‘Reducing the Costs ofSpacecraft Ground Systems and Operations’(RCSGSO), 11–16 June 2007, Moscow,Russian Federation (July 2007)D. Danesy (Ed.)ESA SP-648 // CD Price: 70 Euro

Proceedings of the 2nd IAASS Conference‘Space Safety in a Global World’, 14-16 May2007, Chicago, USA (July 2007)D. Danesy (Ed.)ESA SP-645 // CD Price: 70 Euro

ESA Contractor ReportsRadio Frequency Transmitter for MultimediaGround Terminals – Final Report (May 2004)ND SatComESA CR(P)-4580 // CDPrice: 25 Euro

SDR Technology in Space – Final Report(June 2006)Atos Origin, SpainESA CR(P)-4583 // CDPrice: 25 Euro

M2 – ASIC System Evolution – Executive Summary (November 2006)Austrian Aerospace, AustriaESA CR(P)-4581 // CDPrice: 25 Euro

Preparation Study of Investigations intoBiological Effects of Radiation – Final Report(December 2006)Univ. of Napels Federico II, ItalyESA CR(P)-4585 // CDPrice: 25 Euro

Minimux – Final Report (October 2006)Tesat, GermanyESA CR(P)-4582 // CDPrice: 25 Euro

LARI – Low Cost Remote Surveillance &Metering Satellite Services Feasibility Study – Final Report & Executive Summary (March 2006)VitroCiset, ItalyESA CR(P)-4584Price: 25 Euro

Multimedia Ground Terminals & Equipment:Fast Forward – Final Report (December2006)Advantech Satellite Networks, CanadaESA CR(P)-4586 // CDPrice: 25 Euro

Breadboarding of Feed Cluster for aReflector-Based Multiple Beam SAR Antenna– Summary Report (January 2007)EADS Astrium GmbH, GermanyESA CR(P)-4587 // CDPrice: 25 Euro

Enhancement of Diffusers BSDF Accuracy – Final Report (November 2007)TNO Science and Industry, The NetherlandsESA CR(P)-4588 // CDPrice: 25 Euro

Satellite Communication System Elements,Technologies and Applications: Opportunitiesfor Start-Up Projects – Executive Summary(June 2004)ComSine Ltd, UKESA CR(P)-4589 // CDPrice: 25 Euro e

New issues

PublicationsThe documents listed here have

been issued since the last

publications announcement in the

ESA Bulletin. Requests for copies

should be made in accordance

with the Table and Order Form

inside the back cover

Resolution on the European Space Policy;ESA Director General’s Proposal for theEuropean Space Policy (June 2007)A. Wilson (Ed.)ESA BR-269 // 37 ppPrice: 10 Euro

ESA NewsletterConnect – ESA TelecommunicationNewsletter (May 2007)N. Menning & P. Clissold (Eds.)No Charge

ESA Special PublicationsBed-Rest Studies in the Spaceflight Era(1986–2005) – A ReviewB. Battrick (Ed.)ESA SP-1305 // 114 ppPrice: 30 Euro

Proceedings of the Envisat Symposium2007, 23–27 April 2007, Montreux,Switzerland (July 2007)H. Lacoste & L. Ouwehand (Eds.)ESA SP-636 // CD (2 volumes)Price: 80 Euro

Proceedings of DASIA 2007, DAta SystemsIn Aerospace, 29 May – 1 June 2007, Naples,Italy (August 2007)

A full listing of ESA publications is available atwww.esa.int/publications

PubsB131 8/1/07 5:13 PM Page 72